Geology of the Mercur Gold Camp, Utah

The gold deposits at Mercur, Utah, are typical epithermal deposits. Ore deposition probably occurred at depths of 1,000 feet or less with low temperatures ranging from 200 o + to 100 oC. The most prominent type of metasomatism associated with the gold deposits is silicificatlon accompanied by sericitizatlon. Sulfur isotopic data for the deposits have a mean value of of +7.9 permil and have a spread of values which correlate with sulfur isotopic data for hot spring deposits. Mercur is of interest structurally because of the occurrence of two breccea pipes believed to have originated as explosive events. Organic extraction and analysis by infrared spectroscopy of carbon-rich samples from Mercur, Utah, and Carlin and Getchell Mine, Nevada, show the presence of alkane and carbonyl groups. The carbon present in all three areas is believed to be the result of reduction of hydrocarbons to carbon by the chemical conditions that once existed in the hydrothermal areas.

THE THI! GEOLOGY GEOLOGY OP OF THE THI! MERCUR MERCUR GOLD GOLD CAMP, CAMP. UTAH bby y E dwin M ichael Edwin Michael Guenther Guenther A h e s i s s uubmitted b m i t t e d tto o tthe h e ffaculty a c u l t y oof f the the A tthesis U n i v e r s i t y oof f U t a h iin n ppartial a r t i a l ffulfIllment u l f i l l m e n t oof f tthe h e requirements requirements Universlty Utah ffor o r tthe h e ddegree e g r e e of of M a s t e r oof f SOience Science Master in in Economic E c o n o m i c Geology Geology D e p a r t m e n t of o f GeologIca G e o l o g i c a ll and a n d Geophysical G e o p h y s i c a l SCiences Sciences Department U n i v e r s lty i t y of o f Uta U t ah h Univers J u n e 1973 1973 June THE GEOLOGY OF THE MERCUR GOLD CAMP, UTAH by by E dwin M ichael Edwin Michael Guenther Guenther C opyright © 1 9 7 3 E dwin M ichael cOPyright~1973 Edwin Michael Guenther Guenther No t oof f tthis h i s bbook ook m a y bbe e rreproduced e p r o d u c e d bby y aany n y mechan m e c h a nic i cal a l ,, No ppaa rrt may pphotographic. h o t o g r a p h i c , oor r eelectronic l e c t r o n i c pprocess r o c e s s ffor o r ppublic u b l i c or or ppriva r i v a tte e uuse se w ithout w r i t t e n ppermission e r m i s s i o n ffrom r o m tthe h e autho a u t h orr . without written This thesis for the Master of Scienoe Degree by EdN1n n.lchael Guenther UNIVERSITY OF UTAH LIBRARIES AC KNO iJU: LG 11E NT S The fol1cHing thesis �ms originated, arid I=0.1d for by the author. h1s re��8:'cl, effr)Tts by 'i:he instruments and I would Goodwin, the lite and 1'he author was hindered lack of funds. to the.nk Dre Prof. M.P. M.L. Jensen, the author conduct som� Bureau of Mines author who has Development allowlL� the valued at Utahe reading l�ke to thank the in this to the U.S. samples. , The for graclcusly thesis at the University the of wishes of Great Northern Resource unfortunately restl'1cted from present1ng all observat1ons or conclusions that reached d.uring the publication of information Development the author is were it. with Great Northern Re sou rc e gratuitous Pursuant . ln�erpretatlon of like to thank them $275.000 H for improving for some carbon assays of would . sulfur isotope analyses and I would worked ..T M.L • . Jensen for letting making constructive criticisMS on data. Dro Erickson for critically I wo uld also like to thank Dr. isotope in lack of availabl1i ty of the manuscript and making suggestions sulfur researched. investigation of th0 area. CONTENTS CONTENTS PPage age Abs b s tr9.c t r a c tt .•.. . Co •••• IIntroGuct:lr.n. ntroduction. A • .. • ••••••••••••••••••• ., •••••••••• . _ • • • • • • • • • • • • • • • • • e , Geologie A.. G A eologic Mapping • eo. • • • . • • ~ • • • • • • • • • • • • ~ CII • • • e ~ • • • • • • ~ x • .X .... • • ~ 1 1 ~ .2 .2 B.• I/O I/oc·9.tlon L C L l u i O••••••••••••• » » 4 « * t » f i « « » » « #~ »•••••••••• » » t « » i » » # # »" «••••••••• » » » « « e » » J3; c. C. .... ........... .. Analytje.al A n a l y t i c a l PProcedures. rocedures » ~ D.. B Brief History Mining D rief H i s t o r y oof f M ining ~ , .3 .3 Activities Activities i_rea iin n tthe he A r e a . . . . . . . . . . . . • . • . . .. . • . . . . . . . . . . • 5 5 Stratigra.phy. Stratigraphy ... ....... . . ................... .. .. •• 9 . *9 Structure S t r u c t u r e ••.••••••••••••••••••• < • • • • • • • • • • • • A, 12 , . . . l 6 ~s Patterns Intrusiva I n t r u s i v e Rocks H o c k s ••• A . Kersantite Kersant ite .... • • • • • • • • • • • • • • • • • • ~ • • • 19 . . . . .• 24 24 • • • • • • • • • c • • • • • • • • • . . . . . . . . . . . • ~ • • • • • • • • • • • • . . . . . . Q - • • • • ...24 24 . ................ ... 24 Eagle Hill Rhyolite ••••• ·. ..... .. .. . . 1 • f)truc tural Rela.tions. ·.. . .. ..... .. . . • 26 loe;y •••••••••••• ·.... . .......... • 28 2" Pe t B . Bird's-eye B i r d ' s - e y e Porphyry. Porphyry... B. Eagle 1. Hill ~ ~ Rhyolite Structural ~ ~ Relations 2 . P e t r1'0 ology B . Gold G o l d Ledge. Ledge B. ~ 0 • o « 0 • • • • 28 • • • .• . • . • . •. •. .• .• . • . • . •. 0. .• 3)11 • «• •• •• •• •0 •• •• •• •• . • • e _ • • • • • • • • • • • • • • • • • • • ~ ~ ~ ~ ~ ~ • • • • • .• ..)2 32 • • • • • • • W e a t h e r i n g * • . •. . .• •• •• •• •• •• •• • •• •• .• • •c • • . .• .• . • • • ~ 25 26 , • Ledge. A. A . S i 1v e r L edge ...24 ~ Altera.tion A l t e r a t i o n of o f the t h e Sedimentary S e d i m e n t a r y Rocks. Rocks c. C• •••• .. ........ ............. ..16 Patterns. ......................... • 19 Breccia Pipes Breccia P i p e s .•• , B . Joint Joint D. c. C, ~ _ • •. )6 36 ..•40 40 PClge Page .t.,lt;er::;.tion E~Lc;le ... 4) A l t e r a t i o n of o f tthe he E a g l e lUll H i l l Intrusi~e I n t r u s i v e •....... •..,.. 43 Tt~·: T h e Golfl G o l d :;3r.l;slts Dsposits oe~ •• c ••••• Elemental E l e m e n t a l Analyses A n a l y s e s of o f Reck R o c k Samples S a m p l e s ••• o.~ ••• ................... . . . . . . . 48 48 # 9 ••• ••••• 52 5^ IL.pllcations I m p l i c a t i o n s of o f C8:z.'bon C a r b o n Si.i1G. a n d Organic O r g a n i c Co~poun~3 C o m p o u n d..... s . . . . 056 .56 Da.taD a t a ••• . . « . Oq > . .». . . StL!.fur Sulfur Isotopic Su:nmary S u m m a r y and a n d Reco7!llnend8tions. Recommendations , • • • • • • h • • • . • • • 0• • •• • •• •• ... • . 63 63 • • • • • • ~ ~ . . •• . . . . . . . . . . . .6.. • .73 •73 „. *. ~ ~ Selected S e l e c t e d References R e f e r e n c e s •••••••••••••••••••••••••••••• • • • . • • • • • • • • • • • • • • • • • . • » 76 76 V 1i ta t a .... e ........ It •• ,f' .• • 0, •••• & • II , vi vi • o!# • • • • • • • • ~ . . .80 .80 . . . . . . . 19 ILLUSTaAT I L L U S T R A T IIO~JS ONS P.s.ge Page F i g u r e 1.--In1ez 1.—Index Figure m a p showing s h o w i n g llecation o c a t i o n of of ~ap 1-19j'·8ur:l i s j u i i r j Uta:l U t a n ••.• •., . ........ • • . • • • . . *o. • . •$.• • . a" • . . ••• , • - • - • • . * • #44 & (t 22o--View , — V i e w of o f Mercur H e r c u r from f r o m Eagle Eagle W 9 Hlll H i l l••••••••• . . . . . . . . .6 6 Sun~{~· q4J~1 ..l.. 33. . . --V_,~.··.··.T — V i _«• w oof· f 1~.A_rcu·.-.~. M e r c u r ff-o~ r..1..o m S unrise H i l l .. .,, ~ ~.AU •••• .... ..4. .. )0 ' _ ...... ~. ••••• 66 4.--Geologlc map Utah 4.—Geologic m a p of o f Mercur. Mercur, U t a h .•••••••••• . . . 13 13 55.--Collapsb . — C o l l a p s e bbreccia r e c c i a Geyder-Marion Geyser-Marion -Sacramento m ine 66 ,..— --Sacr&mento mine mine m i n e••• . , , 16 16 vv~.e~l i e w .••••••••••••••••• . . . . . .e17 1? ? . — C l o s e - u p of o f bbrece1a r e c c i a .•••••••••••••• .« . •. •. •. 17 1? 7c--Close~up 9 ,• 8 , - - C o n t o u r diagram d i a g r a m oof f Joint j o i n t distribution.20 distribution,20 8.--Contour 9 . — P l o t of o f strike strike 9.--Plot d i r e c t i o n s ••••• * dlrec~~ons Q ••• *., ,21 ~.~.21 10.--Plot 1 0 , — P l o t oof f fault f a u l t strike s t r i k e d1rections d i r e c t i o n s ••••••• 21 21 111~ao~Index 1 * — I n d e x map m a p of o f 19neous i g n e o u s rocks r o c k s llccation o c a t i o n ..... • .25 25 12.--Close-up Nereur 1 2 . - ~ C l o s e » u p of of M e r c u r jj3spero1d a s p e r o i d types~ t y p e s . ••• . . . 334 4 113~--Photo~lcrograph 3 . — P h o t o m i c r o g r a p h oof f anhedral a n h e d r a l jjasperoid.35 a s p e r o i d ,35 14.--Photomlcrograph 1 4 . - - P h o t o m i c r o g r a p h of o f ttyp1cal y p i c a l jjasperoid a s p e r o l d .••. 35 35 1 5 . — P h o t o m i c r o g r a p h of o f gold g o l d oore r e sequence s e q u e n c e•• . . 39 39 15.--Photomlcrcgraph l6.--·Photo 1 6 . — P h o t o showJ.ng s h o w i n g rrelationshtps e l a t i o n s h i p s between between weathered w e a t h e r e d and a n d uunweathered n w e a t h e r e d oore r e .••••••••• , . » . , « , . ,42 42 PPage age taOH organ FFii ggure u r e 119 9 ..--Inf - - I n f r ra a r re ed d s::;pectra p e c t r a oof f NaOH o r g a n ic ic eextract1ons x t r a c t i o n s *• • •• • ••••••• •~ .• .• .• .c .•.•.•.•. •. •. •• • •. 660 0 NH AC 220 0 .--Infrared I n f r a r e d sspect p e c t rraa oof f NH^Ac orga o r g a nic nic 4 eex x tt rrao.c c tti i oons n s •. •••• •• ••••.••• • •••••• •••- 6 11 --Nap 221. 1.— M a p sshowing h o w i n g ss uulfur l f u r ii ssotope otope ccollec o l l e c tt1on i o n ss1tes i t e s ,• t ss umple ample . •• •• •• •• •• 222.--Reac 2 . — R e a c ttions i o n s iin n aa ffumarollc umarolic "1111 viil 8 • . .•.•.•. •. .•.•66S 5 • c o n d u i t... . . . .. *.. 668 8 conduit TABLES TAELES PPage age 11.. At A t oo51ic m i c llbso a b s o rptlon r p t i o n val v a l uues e s •• 45 • ••••••••••••••••••• 45 22. . Q u a l i t a t i v e eem m i ssion s s i o n sspectrogr p e c t r o g r aphic a p h s ar~lyses a n a l y s e s •• . . 55J3 Qualitative 33. * SSeml e m i -- qu~ntltatlve q u a n t i t a t i v e eemission mission s p e c t r o g raphic raphlc spectrog aa nnalyses a l y s e s .......... . A . . . . .. . . ..... . .. . ~. .... . . . ... .* ... . . ... . . . . . . . * . . * . . » . . . » 5^* 54 0 " ..................... . Sul 44. . S u l ffur u r ii ss ootopic t o p i c ddata a t a . •••••••. • ••. •• •••••••• • •••• 66 66 » ABSTRACT The gold g o l d teposits d e p o s i t s at a t M~rcur, M e r c u r , Utah, U t a h , ar~ a r e typical typical epithermal e p i t h e r m a l deposits. deposits. Ore O r e deposition d e p o s i t i o n proba"oly p r o b a b l y occurred occurred at a t d,..;pths d e p t h s 0;.' o f 1.000 1 , Q 0 0 feet f e e t or o r less l e s s with w i t h low low .... ranging fran ~OO ranging 200 from terr:p~ratures temperatures + to 100 0 C. r most prominent type 'he + to The m o s t 0O Q 100 0 , prominent type of metasomatism associated with the gold deposits 1s of metasomatism associated with the gold deposits accompanied by sericitization. siliclfic~tion silicificatlon accompanied by is Sulfur sericitizatlon. Sulfur isotopic d9.t-a fOT the deposits ha.ve a. mean value of isotopic for the data deposits have a mean v a l u e <5 1 s3 • of of +7.9 permil and have a spread of values which cOl'relates of +7.9 permil and have a spread of values which correlate with sulfv.r isotopic data for hct; spring deposits. with sulfur isotopic data for hot spring deposits. lJlercur 1s of interest struc{;urally b~cause of the Mercur because of is of interest structurally the occurre!me of two breccea pipsE believed to have occurrence of two breccea pipes believed to have originated as explosive events. originated as explosive events. Org~nic extraction a.nd analysis by infra.red Organic extraction and analysis by infrared spectroscopy of carbon-rich samples from Mercur, Utah, spectroscopy of carbon-rich samples from Mercur, Utah, and Carlirl and Getchell Mine, Nevada, shDw the preset'!ce and Carlin and Getchell Mine, Nevada, show the presence of alkane and carbonyl groups. The carbon present in of The alkane and carbonyl groups. carbon present in all three areas is believed to be the result of all three areas is believed to be the result of reduction of hydrocarbons to carbon by the chemical reduction of hydrocarbons to carbon by the chemical conditions that once existed in the hydrot.hermaJ. areas. conditions '\ that once existed in the hydrothermal areas. INTRODUCTION INTRODUCTION The T h e first f i r s t comprehensive c o m p r e h e n s i v e work w o r k on o n the t h e Mercur M e r c u r area area was when was w a s done d o n e bby y Spurr S p u r r (1894-95) (1894-95) w h e n the t h e district district w a s still still in i n its i t s infancy i n f a n c y as a s a gold g o l d pproducer. roducer. The T h e author a u t h o r is is indebted i n d e b t e d tto o his h i s descriptions d e s c r i p t i o n s of o f the t h e mine m i n e locations, locations, workings, w o r k i n g s , and a n d ~eologic g e o l o g i c settings--especially s e t t i n g s — e s p e c i a l l y reg~rding regarding the t h e presence p r e s e n c e oof f carbon. carbon, Spurr S p u r r also a l s o gave g a v e the t h e first first detailed d e t a i l e d account a c c o u n t of o f the t h e hhydrothermal y d r o t h e r m a l alteration a l t e r a t i o n oof f the the bedrock b e d r o c k aassociated s s o c i a t e d with w i t h the t h e deposits. deposits. Some S o m e oof f his his interpretations were i n t e r p r e t a t i o n s as a s to t o alteration alteration w e r e later l a t e r discredited discredited by Butler who Spurr by B u t l e r (1920, ( 1 9 2 0 , pp., 390) 390) w h o found f o u n d that t h a t what what S p u r r had had called were c a l l e d altered a l t e r e d intrusive i n t r u s i v e sills sills w e r e in i n reality r e a l i t y altered altered l i m e s t o n e or o r shale s h a l e layers. layers. limestone The T h e first f i r s t comprehensive c o m p r e h e n s i v e study s t u d y of o f tthe h e geology geology and a n d ore o r e deposits d e p o s i t s of o f the t h e southern s o u t h e r n Oquirrh O q u i r r h Mountains M o u n t a i n s was was done d o n e by b y Gilluly G i l l u l y (1932) ( 1 9 3 2 ) during d u r i n g the t h e summers s u m m e r s oof f 1926 1926 qnd a n d 1927. 1 9 2 7 , but b u t he h e did d i d not n o t do d o a detailed d e t a i l e d study s t u d y oof f the the ore o r e deposits d e p o s i t s of o f the t h e Mercur M e r c u r area a r e a because b e c a u s e hhe e states states that were t h a t the t h e mines mines w e r e inaccessible i n a c c e s s i b l e at a t the t h e time t i m e oof f his his investigation. Investigation. His H i s discussion d i s c u s s i o n of o f the t h e alteration a l t e r a t i o n of o f the the igneous i g n e o u s rocks r o c k s and a n d of o f the t h e sedimentary s e d i m e n t a r y rocks r o c k s of o f tthe h e area area hhas a s been b e e n most m o s t hhelpful e l p f u l to t o the t h e author a u t h o r in i n delineating delineating what w h a t hhad a d been b e e n done d o n e in i n tthis h i s area. area. Rigby Brigham R i g b y and a n d Bissell B i s s e l l (1959) ( 1 9 5 9 ) of of B r i g h a m Young Y o u n g University University were w e r e the t h e next n e x t investigators i n v e s t i g a t o r s to t o conduct c o n d u c t research r e s e a r c h iin n the the 2 ~rea. area. c~mp camp In I n 1955. 1 9 5 5 • they t h e y supervised s u p e r v i s e d a geologie g e o l o g i c summer s u m m e r field field during d u r i n g which w h i c h the t h e area a r e a w~s w a s remapped r e m a p p e d at a t a scale s c a l e of of 1 : 1 2 , 0 0 0 for f o r the t h e first f i r s t time t i m e since s i n c e Gilluly G i l l u l y (1932) ( 1 9 3 2 ) had had 1:12.000 m a p p e d the t h e area. area. mapped T h e latter's l a t t e r s map m a p was w a s made m a d e by b y plane p l a n e table table The 1 a n d open-sight o p e n - s i g h t alidade a l i d a d e on o n a topographic t o p o g r a p h i c b'lse b - i s e wi w i th t h Aa qnd s c a l e of o f 1:31.250 1 : 3 1 , 2 5 0 (Gilluly. ( G i l l u l y , 1932. 1 9 3 2 , p. p . 4). 4). scale T h e author, author, The d u r i n g a reconnaisance r e c o n n a i s a n c e examination e x a m i n a t i o n of o f the t h e a~rea r e a in i n the the during s u m m e r of o f 1971. 1 9 7 1 » observed o b s e r v e d sufficient s u f f i c i e n t previously p r e v i o u s l y overlooked overlooked summer s t r u c t u r a l features, f e a t u r e s , alteration a l t e r a t i o n patterns, p a t t e r n s , and a n d stratigraphic stratigraphic structural f i e l d relations r e l a t i o n s which, w h i c h , because b e c a u s e of o f their t h e i r importance i m p o r t a n c e to t o the the field e c o n o m i c geology g e o l o g y of o f the t h e area. a r e a , led l e d the t h e author a u t h o r to t o undertake undertake economic t h i s study. study. this Geologic G e o l o g i c Mapping Mapping Geologic G e o l o g i c mapping m a p p i n g of o f the t h e Mercur M e r c u r area a r e a at a t a scale scale o f 1:6,000 1:6,000 w a s uundertaken n d e r t a k e n by b y the t h e author a u t h o r during d u r i n g the the of was summer s u m m e r 1972. 1972. The T h e geology g e o l o g y was w a s pplotted l o t t e d on on. a topographic topographic map which was made bbase ase m ap w hich w as m a d e bby y pphotographically h o t o g r a p h i c a l l y enlarging enlarging tthe he U .S. G e o l o g i c a l Survey's Survey's M ercur, U tah, U.S. Geological Mercur, Ut~h. ttopographic o p o g r a p h i c qquadrangle. uadrangle. 115 5 minute minute A e r i a l pphotographs hotographs w e r e uused s e d for for Aerial were ppreliminary r e l i m i n a r y study s t u d y oof f the t h e aarea. rea. T h e sscale c a l e oof f tthe he The included included ggeologic eologic m a p ((Fig. F i g . 44) ) w a s ddecreased e c r e a s e d ffrom r o m the t h e original original map was tto o rreduce e d u c e tthe h e ccost o s t oof f duplication. duplication, Silicification was S i l i c i f i c a t i o n iin n tthe h e ggold o l d oore r e ssequence equence w a s not not mapped m a p p e d bbecause e c a u s e oof f tthe h e ddifficulty i f f i c u l t y oof f ttracing r a c i n g the the )3 alteration a l t e r a t i o n zones. zones, Jasperoid was Jasperoid w a s mapped m a p p e d bbecause e c a u s e it it represented mapable r e p r e s e n t e d easily easily m a p a b l e areas. areas. Location Location Mercur, Utah, Mercur, U t a h , is i s lloc~ted o c a t e d at a t the t h e head h e a d of o f Mercur Mercur Canyon C a n y o n (formerly ( f o r m e r l y Lewiston L e w i s t o n Canyon) C a n y o n ) in i n the t h e southern southern Mountains ppart a r t of o f the t h e Oquirrh Oquirrh M o u n t a i n s about a b o u t 70 7 0 miles m i l e s by b y road road southe'-lst Lake s o u t h e a s t of o f Salt Salt L a k e City C i t y (Fig. ( F i g . 1). 1). The T h e terrain t e r r a i n of o f the t h e surrounding s u r r o u n d i n g hills h i l l s is i s one o n e of of moderate m o d e r a t e rrelief. elief. The maximum The m a x i m u m relief r e l i e f bbetween e t w e e n the the ghost g h o s t town t o w n of o f Mercur M e r c u r and a n d Eagle E a g l e Hill H i l l is i s about a b o u t 1,)00 1 , 3 0 0 feet. feet. Analytical A n a l y t i c a l Procedures Procedures The T h e aauthor, u t h o r , during d u r i n g the t h e ccourse o u r s e of o f the t h e present present investigation, i n v e s t i g a t i o n , uused s e d several s e v e r a l instrumental i n s t r u m e n t a l techniques techniques to t o gain g a i n information i n f o r m a t i o n needed n e e d e d to t o solve s o l v e tthe h e geologic g e o l o g i c problems. problems. X-ray X - r a y diffraction d i f f r a c t i o n and a n d fluorescence f l u o r e s c e n c e techniques t e c h n i q u e s were w e r e used used for mineral for m i n e r a l determinations. determinations. Atomic A t o m i c absorption a b s o r p t i o n and and emission e m i s s i o n spectroscopy s p e c t r o s c o p y techniques t e c h n i q u e s were w e r e uused s e d for f o r elemental elemental determinations. determinations. Infrared I n f r a r e d spectroscopic s p e c t r o s c o p i c and a n d gas gas chromatographic were c h r o m a t o g r a p h i c techniques techniques w e r e applied a p p l i e d tto o the t h e problem problem of o f organic o r g a n i c identification i d e n t i f i c a t i o n of o f carbonaceous c a r b o n a c e o u s samples. samples. Several were S e v e r a l polished p o l i s h e d sections sections w e r e prepared p r e p a r e d for f o r study study o f the t h e opaque opaque m i n e r a l s of o f the t h e ore o r e sequence. sequence. of minerals T h i n section section Thin studies w e r e uundertaken n d e r t a k e n to t o examine e x a m i n e the t h e mineral m i n e r a l suite suite studies were present, p r e s e n t , ffor o r rock r o c k identification, i d e n t i f i c a t i o n , and a n d for f o r study s t u d y of of 44 UTAH UTAH Great Salt Lake Scale 0 50 miles I—II—I K3 . Solt Lake City O---:=-:::::::;::;===.-,, \I r• , \ Tooel. Co. \ rJ Stockton Figure 1. ~~H , L.\e ) Index ma p s howing the locatlon of Mercur . Ut a h. one mile) (small bar 1n inset re pre s ent s :0. 55 m i n e r a l hhqbits abits miner81 (textures). (textures). Brief Activities B r i e f History H i s t o r y of o f Mining Mining A c t i v i t i e s in i n the t h e Area Area Silver Lewiston, S i l v e r W<3.S w a s d.iscovered d i s c o v e r e d iin n 1869 I 8 6 9 at at L e w i s t o n , tthe h e for-,er former nname a m e of o f Mercur, M e r c u r , bbut u t the t h e ore o r e ppockets o c k e t s pproved r o v e d spotty s p o t t y and and were w e r e soon s o o n exhausted. exhausted. The was T h e district district w a s organized o r g a n i z e d on o n April April 16, Floyd 1 6 , 1870, 1 8 7 0 , aas s tthe h e Camp Camp F l o y d district. district. The T h e early e a r l y mines mines included i n c l u d e d tthe h e Carrie C a r r i e Steele. S t e e l e , Sparrowhawk, S p a r r o w h a w k , Last L a s t Chance, Chance, Silver Marion. Mormon with S i l v e r Cloud, Cloud, M a r i o n , and and M o r m o n Chief Chief w i t h the t h e Carrie Carrie S t e e l e and a n d Sparrowhawk Sparrowhawk m i n e s bbeing e i n g tthe h e bbiggest i g g e s t producers. producers. Steele mines The T h e lloc<3.tion o c a t i o n of o f the t h e Sparrowhawk S p a r r o w h a w k is i s shown s h o w n on o n Figures Figures 2 a n d 3. J, and A f t e r several s e v e r a l yyears e a r s of o f silver s i l v e r pproduction, r o d u c t i o n , the the After town was Lewiston town w a s deserted d e s e r t e d iin n 1880 1 8 8 0 and a n d tthe h e nname a m e oof f L e w i s t o n was was g i v e n to t o another a n o t h e r ttown o w n in i n Cache C a c h e County, C o u n t y , Utah. Utah. given In Arie Mercur I n 1879, 1879» A r i e Pinedo P i n e d o rrenamed e n a m e d tthe h e site site M e r c u r after after hhis i s discovery d i s c o v e r y of o f mercury m e r c u r y in i n tthe h e area. a r e a , bbut u t hhis i s discovery discovery nroved D r o v e d uneconomical. uneconomical. With W i t h tthe h e discovery d i s c o v e r y oof f gold g o l d in i n the the area was a r e a in i n 1883. 1 8 8 3 » prospecting prospecting w a s again a g a i n resumed r e s u m e d bbut u t tthe h e poor poor extraction milled was e x t r a c t i o n of o f tthe h e gold g o l d from f r o m tthe he m i l l e d oore re w a s discouraging. discouraging. In was Denver, I n 1890. I 8 9 O , a carload c a r l o a d of o f ore ore w a s sent s e n t tto o D e n v e r , Colorado, Colorado, for f o r ttre~tment r e a t m e n t bby y tthe h e nnewly e w l y ddeveloped e v e l o p e d McArthur-Forrest McArthur-Forrest cyanide c y a n i d e pprocess. rocess. The T h e rresults e s u l t s ffrom r o m tthe h e ttest e s t proved proved e n c o u r a g i n g and a n d tthe h e first f i r s t ccyanide y a n i d e pplant l a n t iin n tthe h e United United encouraging S t a t e s was w a s constructed c o n s t r u c t e d at at M anning, U t a h , nnear e a r Mercur Mercur States Manning, Utah, ( G i l l u l y , 1932. 1 9 3 2 , pp.. 123). 123). (Gilluly, 66 FFigure i g u r e 22. . PPanoramic a n o r a m i c vview i e w oof f M ercur, U t a h ffrom rom E a g l e Hlli. Hill. Mercur, Utah Eagle ((1) 1) M ercur H i l l , ((2) 2) S parrowhawk m i n e , (() 3 ) GeyserGeyserMercur H1ll, Sparrowhawk m1ne, Marlon m1ne, Br1ckyard m1ne, M arion m i n e , ((~) 4) B rickyard m i n e , ((5) 5 ) Ingersoll Ingersoll Golden Gate m1ne m1ll sshaft, haft, ( 66) ) G olden G ate m i n e aand nd m i l l ss1te, i t e , ((7) ? ) Ed's Ed's H i l l , ( 8 ) L e w i s t o n P e a k H Lew1ston Peak Pigure). Panoramic view of Mercur. (1) ( 1 ) Sparrowhawk S p a r r o w h a w k m1ne, m i n e , (2) ( 2 ) Ingersoll I n g e r s o l l shaft, shaft, ( 3 ) Geyser G e y s e r -- M a r i o n mine, m i n e , (4) ( 4 ) Mercur M e r c u r Hill H i l l mine, mine, (3) Marlon G o l d e n Gate G a t e m1ne m i n e and a n d m1ll m i l l s1te, s i t e , (6) ( 6 ) Ed's E d ' s H1ll Hill ( 55)) Golden Hlli. ?7 The T h e main m a i n g~old o l d pproduction r o d u c t i o n in i n tthe h e district d i s t r i c t came c a m e from from only o n l y a few~ines, few ^ i n e s . (Geyser-Marion, ( G e y s e r - M a r i o n , Sacramento, S a c r a m e n t o , Mercur Mercur Hill, H i l l , Brickyqrd, B r i c k y a r d , and a n d Golden G o l d e n Gate) G a t e ) all a l l neqr n e a r the t h e town town of o f Mercur. Mercur, The Geyser were The G e y s e r and a n d Marion M a r i o n mines mines w e r e Jjoined o i n e d in in 1897 1 8 9 7 to t o form f o r m the t h e Geyser-Marion G e y s e r - M a r i o n mine. mine. The T h e Go1den G o l d e n Gate Gate mill m i l l was w a s constructed c o n s t r u c t e d in i n 1898 I 8 9 8 and a n d in i n 1899 1 8 9 9 the t h e Mercur Mercur Mines with Mining M i n e s Co. G o . combined combined w i t h the t h e Mercur M e r c u r Gold Gold M i n i n g qnd and Milling which M i l l i n g Co. Co. w h i c h resulted r e s u l t e d in i n the t h e ores o r e s from f r o m the t h e Mercur Mercur Hill Golden H i l l and a n d the the G o l d e n Gate G a t e mines m i n e s being b e i n g milled m i l l e d at a t the t h e Golden Golden Gate m ill. Gate mill. I n 1913, 1 9 1 3 , tthe h e Consolidated C o n s o l i d a t e d Mercur M e r c u r Gold G o l d Mines Mines In Co., which most Co., w h i c h accounted a c c o u n t e d for for m o s t of o f tthe h e gold g o l d production p r o d u c t i o n in in t h e district, d i s t r i c t , ceased c e a s e d mining m i n i n g operations o p e r a t i o n s bbecause e c a u s e of o f the the the fqiling f a i l i n g ore o r e grade. grade. The T h e town t o w n of o f Mercur M e r c u r soon s o o n dwindled d w i n d l e d although although the t h e Geyser-Marinn G e y s e r - M a r i o n and a n d Sacramento S a c r a m e n t o mines m i n e s operated o p e r a t e d for f o r several several yyeqrs e a r s thereafter t h e r e a f t e r (Franklin ( F r a n k l i n and a n d Miller, Miller, 1938, 1 9 3 8 , pp.. 2-4). 2-4). The was T h e Sacramento S a c r a m e n t o mine mine w a s tthe h e only o n l y mine m i n e in i n the t h e area a r e a to t o yield yield c i n n a b a r and a n d gold g o l d and a n d produced p r o d u c e d a reported r e p o r t e d 3.538 3 # 5 3 8 flasks flasks cinnabar of p. o f mercury m e r c u r y (Howqrd, ( H o w a r d , 1913. 1 9 * 3 . P» 13). 13)- In I n 1933 1 9 3 3 tthe h e Snyder S n y d e r Mines M i n e s Co. C o . began b e g a n working w o r k i n g the the ttailings a i l i n g s ddumps u m p s to t o the t h e south s o u t h of o f Mercur M e r c u r at a t the t h e old o l d town town site Manning. s i t e of of M anning. At A t about a b o u t the t h e same s a m e time, t i m e , the t h e mines mines at a t Mercur M e r c u r were w e r e re-opened r e - o p e n e d bby y the t h e Snyder S n y d e r Mines M i n e s Co. C o . with with tthe h e ores o r e s first f i r s t bbeing e i n g shipped s h i p p e d to t o Manning M a n n i n g for f o r milling. milling. Later, L a t e r , in i n 1937, 1 9 3 7 , tthe h e milling m i l l i n g operations o p e r a t i o n s were w e r e shifted s h i f t e d to to M e r c u r (Franklin ( F r a n k l i n and and M i l l e r , 1938. 1 9 3 8 , pp.. 5). 5). Mercur Miller. T h e y mined m i n e d the the They easily w o r k a b l e low-grade l o w - g r a d e surface s u r f a c e ores o r e s in i n quarries q u a r r i e s on on e8sily workable 8 a lease l e a s e bqsis b a s i s (Franklin ( F r a n k l i n and a n d Miller. M i l l e r , 1938, 1 9 3 8 , p. p . 5). 5)• They They also worked also w o r k e d the t h e rremaining e m a i n i n g ore o r e in i n tthe h e Golden G o l d e n Gate G a t e mine mine tthrough h r o u g h tthe h e IIngersoll n g e r s o l l shaft s h a f t (Fig. ( F i g . 22). ). The mines T he m ines were were again a g a i n shut s h u t down d o w n in i n 1942 1 9 ^ 2 bbecause e c a u s e oof f a governmental g o v e r n m e n t a l decree decree closing c l o s i n g gold g o l d mines. mines. The Dome Gold Mining Co. T h e Mercur M e r c u r Dome Gold M ining C o . fformed o r m e d iin n 1937 1937 mined west Mercur m i n e d from f r o m an a n area a r e a jjust ust w e s t oof f M e r c u r off o f f tthe h e included included geologic g e o l o g i c map m a p (Fig. ( F i g , 4). 4). The Mines T h e Bureau B u r e a u of of M i n e s rreported eported ppresence r e s e n c e of o f vvanadium a n a d i u m iin n a carbonaceous c a r b o n a c e o u s shale shale mine iin n tthis his m ine the the horizon horizon (King p.. 1). ( K i n g aand n d Wilson, W i l s o n , 1949. 19^9. P 1). The mines The m i n e s tto o tthe h e south s o u t h at a t Sunshine S u n s h i n e iincluded n c l u d e d the the Overland O v e r l a n d aand n d tthe h e Sunshine. Sunshine, The mined T h e ggold o l d ore ore m i n e d at a t Sunshine Sunshine was Mercur. rreportedly eportedly w a s similar s i m i l a r tto o tthe h e ores o r e s from from M ercur. Jasperoid, Jasperoid, s i m i l a r tto o that t h a t at a t Mercur. M e r c u r , is i s present. present. similar The mines West Dip T h e ttwo w o llargest argest m i n e s in i n tthe he W est D i p camp c a m p were were Norma tthe he N o r m a aand n d tthe h e La L a Cigale. Cigale. The T h e ggold o l d oore r e hhere e r e aalso l s o was was rreportedly e p o r t e d l y similar s i m i l a r tto o tthe h e ores o r e s ffrom r o m Mercur, M e r c u r , bbut u t tthe he hhad a d only o n l y llimited imited Proctor Proctor camp camp production. production. (lU (in Bissell. p.. 2214) B i s s e l l , 1959. 1959# P 1 4 ) states states that that over metal mined o v e r $25,500,000 $ 2 5 * 5 0 0 , 0 0 0 in In m e t a l vvalues a l u e s hhave a v e bbeen een m i n e d aat t Mercur. Mercur. Newmont Exploration Ltd. IIn n 1969, I969* N ewmont E xploration L t d . uundertook ndertook exploratory exploratory drilling mines d r i l l i n g for f o r ggold o l d mineralization m i n e r a l i z a t i o n aaround r o u n d tthe h e oold ld m i n e s of of Mercur. M ercur. The were T h e results r e s u l t s of o f the t h e drilling drilling w e r e vvery ery and Newmont and N e w m o n t hhas as ~iven given discouraging discouraging most m o s t of o f tthe h e drill d r i l l core c o r e and a n d cuttings cuttings tto o tthe he U tah G e o l o g i c a l and and M l n e r a l o g i c a l Survey's Survey's Utah Geological Mineralogical library. library. core core STRATIGRAPHY STRATIGRAPHY T h e Humbug Humbug F o r m a t i o n and a n d the t h e Great G r e a t Blue B l u e Limestone Limestone The Formation 9re a r e the t h e two t w o stratigraphic s t r a t i g r a p h i c units u n i t s in i n the t h e map m a p aarea. rea. Both Both hhqve a v e been b e e n described d e s c r i b e d previously p r e v i o u s l y by b y Gilluly G i l l u l y (1932) ( 1 9 3 2 ) and a n d by by Bissell B l s s e l l (1959). (1959). The T h e contact c o n t a c t bbetween e t w e e n tthe h e Humbug H u m b u g and a n d the t h e overlying overlying Great G r e a t Blue B l u e Limestone L i m e s t o n e is i s arbitrarily a r b i t r a r i l y placed p l a c e d -at " a t the the top t o p of o f tthe h e highest h i g h e s t orthoquartzite, o r t h o q u a r t z i t e , quartzitic q u a r t z i t i c sandstone, s a n d s t o n e , or or calcarenite Humbugc a l c a r e n i t e of o f significance s i g n i f i c a n c e in i n the the H u m b u g ' ((Bissell, B i s s e l l , 1959. 1959, 1 pp.. 56). 56). G d l l u l y has h a s called c a l l e d tthe h e orthoquartzites o r t h o q u a r t z i t e s lenticular lenticular ~illuly a n d this t h i s author a u t h o r verified v e r i f i e d this this w h e n mapping m a p p i n g tthe h e contact contact and when b e t w e e n the the H u m b u g and a n d tthe h e Great G r e a t Blue. Blue. between Humbug G i l l u l y estimates estimates Gilluly t h a t orthoquartzites o r t h o q u a r t z i t e s comprise c o m p r i s e 30% J0% of o f the t h e Humbug H u m b u g (1932. (1932, that pp.28). . 28). T h e measured m e a s u r e d thickness t h i c k n e s s of o f the t h e Humbug H u m b u g vvaries a r i e s from from The 6 3 5 to t o 645 6 4 5 ffeet e e t for f o r tthe h e uunit n i t in i n the t h e immediate i m m e d i a t e aarea r e a (Gilluly, (Gilluly, 635 1 9 3 2 , pp.. 28; 2 8 ; Bissell, B i s s e l l , 1959. 1 9 5 9 . pp.. 54). 5*0. 1932, T h e age a g e oof f the the The f o r m a t i o n is i s Upper U p p e r Mississippian. Mississippian. formation The T h e Great G r e a t Blue B l u e Limestone, L i m e s t o n e , nnamed a m e d bby y Spurr, S p u r r , iis s tthe h e unit unit from mined f r o m which w h i c h all a l l tthe h e gold g o l d has h a s been been m i n e d 3t a t Mercur. Mercur, It It has mapable h a s been b e e n divided d i v i d e d into i n t o tthree hree m a p a b l e uunits: n i t s : tthe h e Lower Lower Great which Long G r e a t Blue Blue w h i c h is i s Upper U p p e r Mississippian, M i s s i s s i p p i a n , the the L o n g Trail Trail Shale, S h a l e , and a n d the t h e Upper U p p e r Great G r e a t Blue B l u e which w h i c h is i s Lower Lower Pennsylvanian. Pennsylvanian, The T h e -gold " g o l d ledgel e d g e " comprises c o m p r i s e s some s o m e oof f the the bbeds e d s above a b o v e the t h e Long L o n g Trail T r a i l Shale. S h a l e , the t h e Long L o n g Trail T r a i l Shale, Shale, a n d beds b e d s of o f the t h e Lower L o w e r Great G r e a t Blue B l u e below b e l o w the the L o n g Trail Trail and Long 10 10 Sh9le. Shale. The T h e ·silver " s i l v e r lledge· e d g e * is i s in I n the t h e Lower L o w e r Great G r e a t Blue Blue bbelow e l o w tthe h e ·gold " g o l d lledge.· edge." T h e ttotal o t a l thickness t h i c k n e s s oof f the the The formation f o r m a t i o n iis s about a b o u t 3,600 3 . 6 0 0 feet f e e t according a c c o r d i n g tto o Gilluly Gilluly ((1932, 1932, p. --the B-lue p . 29) 29)— t h e Lower L o w e r Great Great B l u e being b e i n g about a b o u t 500 500 feet Long f e e t tthick h i c k and a n d tthe he L o n g Trail T r a i l Shale S h a l e bbeing e i n g about a b o u t 100 1 0 0 feet feet tthick. hick. Upper The The U p p e r Great Great B l u e has h a s bbeen e e n ddescribed e s c r i b e d as as l!1ue m o n o t o n o u s , thick t h i c k tto o m a s s i v e llimestone i m e s t o n e bbeds. eds. monotonous, massive Lower Lower I n the the In G reat B l u e , thin t h i n orthoquartzite o r t h o q u a r t z i t e aand n d sandstone sandstone Gre~t Blue, ccan a n be b e found f o u n d above a b o v e the the H u m b u g contact c o n t a c t in i n tthe h e Mercur Mercur Humbug A s e v e r a l llocations o c a t i o n s in i n Mercur, M e r c u r , only o n l y thin thin Att several layers layers area. area. sandstone sandstone layers w e r e found found w h e r e the t h e contact c o n t a c t should s h o u l d have h a v e been been layers were where bbetween e t w e e n tthe he G reat B l u e aand n d tthe h e Humbug. Humbug. Gre~t Blue T h e section section The a b o v e the t h e Long L o n g Trail T r a i l Shale S h a l e contains c o n t a i n s interbedded i n t e r b e d d e d siltstone, siltstone, above s h a l e , and a n d limestone l i m e s t o n e beds b e d s as a s does d o e s the t h e section s e c t i o n bbelow e l o w the the shale, L o n g Trail T r a i l Shale. Shale, Long o n g Trail T r a i l Shale S h a l e can c a n be b e recognized recognized The LLong b y the t h e fact f a c t tthat h a t siltstone s i l t s t o n e and a n d shale s h a l e bbeds e d s thicken t h i c k e n to to by bbetween e t w e e n 5-10 5 - 1 0 ffeet e e t in i n the t h e unit u n i t whereas w h e r e a s shale s h a l e and and siltstone siltstone bbeds e d s above a b o v e and a n d bbelow e l o w are a r e uusually s u a l l y lless e s s than t h a n two t w o feet feet B i s s e l l (1959, (1959. P Bissell p.. thick. thick. 5 7 ) hhas a s stated s t a t e d that t h a t the t h e Long L o n g Trail T r a i l Shale Shale 57) w a s especially e s p e c i a l l y hhelpful e l p f u l in i n delineating d e l i n e a t i n g structures s t r u c t u r e s in in was the the m a p p e d area a r e a bbut u t tthe h e unit u n i t is i s not n o t easily e a s i l y rrecognizable e c o g n i z a b l e in in mapped t h e field f i e l d bbecause e c a u s e it i t is i s an a n easily e a s i l y eroded e r o d e d unit. unit. the m a p bby y Bissell B i s s e l l and and R i g b y the t h e uunit n i t was w a s mapped mapped map Rigby O n the the On between between vvalleys, a l l e y s , gullies, g u l l i e s , and a n d iow i o w spots s p o t s bbetween e t w e e n hills hills w h i c h one one which m i g h t expect e x p e c t to t o bbe e due d u e to t o tthe he w e a t h e r i n g of of a a shale shale might weathering s e q u e n c e bbut ut sequence c l o s e examination e x a m i n a t i o n shows s h o w s the t h e uunit n i t is i s not not close 11 11 exactly where exactly w h e r e they t h e y mapped m a p p e d it i t or o r in i n some s o m e cases c a s e s is i s not not p r e s e n t at a t all. all. present Alluvium A l l u v i u m consisting c o n s i s t i n g of o f stream s t r e a m gravel g r a v e l asnd n d vvalley a l l e y fill fill cov~rs covers a previously p r e v i o u s l y developed d e v e l o p e d erosion e r o s i o n surface. surface. The T h e gravel gravel to Brickyard t o tthe h e south s o u t h of o f tthe he B r i c k y a r d mine m i n e shows s h o w s stratification, stratification, bbut u t the t h e gravel g r a v e l in i n the t h e ggraben raben w e s t of o f the t h e Brickyard B r i c k y a r d shows shows west n o stratification s t r a t i f i c a t i o n and a n d consists c o n s i s t s of o f Jjumbled u m b l e d rrock o c k fragments. fragments. no T h e thickness t h i c k n e s s of o f the t h e alluvium a l l u v i u m varies. v a r i e s , but b u t is i s commonly commonly The 5-30 5-30 f e e t thick. thick. feet A w e l l - d e v e l o p e d thick t h i c k soil s o i l occurs o c c u r s to to A well-developed t h e east e a s t and a n d south-east s o u t h - e a s t of o f the t h e Mercur Mercur H i l l mine. mine. the Hill T h e alluvium a l l u v i u m is i s presently p r e s e n t l y being b e i n g eroded e r o d e d aaway w a y slowly. slowly, The ppossibly o s s i b l y due d u e to t o uuplift p l i f t of o f the t h e area a r e a and/or a n d / o r the t h e change c h a n g e of of c l i m a t i c conditions c o n d i t i o n s since s i n c e the t h e last l a s t gglacial l a c i a l period. period. climatic STRUCTURE The T h e structural s t r u c t u r a l elements e l e m e n t s in i n the t h e Mercur M e r c u r aarea r e a include include folds, f o l d s , faults, f a u l t s , jjoints, o i n t s , breccia b r e c c i a ppipes, i p e s , and a n d aan n igneous igneous intrusion. intrusion. B o t h regional r e g i o n a l and a n d local l o c a l folds f o l d s occur o c c u r iin n the the Both a r e a with w i t h tthe h e small s m a l l folds f o l d s nnear e a r the t h e intrusion i n t r u s i o n apparently apparently area bbeing e i n g related r e l a t e d tto o tthe h e igneous i g n e o u s intrusion. intrusion. M o s t oof f the the Most f a u l t s are a r e small s m a l l with w i t h displacements d i s p l a c e m e n t s less l e s s tthan h a n 550 0 feet. feet. faults Mprcur M e r c u r is i s on o n tthe h e east e a s t flank f l a n k of o f tthe h e Ophir O p h i r anticline, anticline, a broad, b r o a d , asymmetrical a s y m m e t r i c a l structure s t r u c t u r e of o f Laramide L a r a m i d e age. age. The The general g e n e r a l strike s t r i k e of o f tthe h e east e a s t limb l i m b of o f the t h e anticline a n t i c l i n e shown shown in N JOoW i n the t h e northern n o r t h e r n part p a r t of o f the t h e map m a p (Fig. ( F i g . 4) 4 ) is i s aabout bout N 30°W and a n d the t h e strike s t r i k e of o f the t h e anticlinal a n t i c l i n a l axis, a x i s , taken t a k e n from f r o m Bissell Bissell 0 and N 220 W.. a n d Rigby's R i g b y ' s map m a p (1959, ( 1 9 5 9 t plate p l a t e 1), 1 ) , is i s about about N 0°W In I n the the southern s o u t h e r n part p a r t of o f the t h e map m a p area a r e a around a r o u n d the t h e Eagle E a g l e Hill Hill I n t r u s i v e , dip d i p and a n d strike s t r i k e of o f the t h e bbeds e d s deviate d e v i a t e ffrom r o m the the intrusive, t r e n d of o f the t h e Ophir O p h i r anticline. anticline. trend T h e s e changes, c h a n g e s , overlooked overlooked These bby y previous p r e v i o u s investigators, i n v e s t i g a t o r s , seem s e e m tto o indicate i n d i c a t e a forceful forceful e m p l a c e m e n t of o f the t h e intrusive i n t r u s i v e after a f t e r rregional e g i o n a l foldingo folding. emplacement S e c o n d a r y folding f o l d i n g on o n the t h e nnorth o r t h side s i d e of o f the t h e intrusive intrusive Secondary f o r m s a small s m a l l sync s y n c line. line. forms A small s m a l l anticline a n t i c l i n e also a l s o occurs occurs A t o the t h e south s o u t h of o f the t h e map m a p area a r e a on o n the t h e south-west s o u t h - w e s t rrldge i d g e of of to E a g l e Hill. Hill. Eagle B o t h structures s t r u c t u r e s deviate d e v i a t e from f r o m tthe h e axial a x i a l trend trend Both o f the t h e Ophir O p h i r anticline. anticline. of O n e small s m a l l syncline s y n c l i n e ooccurs c c u r s oon n the the One h i l l to t o the t h e east e a s t of o f tthe h e Golden G o l d e n Gate G a t e mine. mine. hill IIts t s axial a x i a l plane plane nnearly e a r l y parallels p a r a l l e l s the t h e larger l a r g e r structural s t r u c t u r a l feature f e a t u r e of o f tthe h e area-area 1) 13 GEOLOGIC MAP OF MERCUR, UTAH EXPLANATION .. " z Alluvial deposits Stre-lll !;ravel and vall",! fill ::: Breccia c :::> o Kaolinized and Silicified Intrulive Eagl. Hill Rhyolite rntrulHv. . .hiterhyollteWJ.th 50m",o"artz,al'lJll-dine. andbiotitephenocry"tB Contad I/;J.shedwttereapproximatelylocaled; dottecl..h .. reconc""led ............ . ~---Fault, shawing dip Mgbu ~~~t' Dashed ..bereapproXl:matclylocatedj dotted ..here conc~aled. ~id~pthro- sJ.de; D, do.ntbrQft Mgbl Great Blue Llm•• lane Mgt!:ie~~:!~E:~~3 ~~~ ~e 6~1~;~~~P5, .. ~ Strike and Mgbu,uFP"rwember; thick to llmestonebeds dip of bed, .,~ Vertical and Inclined shafts Hgl.1.1" .... r .. elllb<lT; thick to ,""ssivelJ.meston.ebeds Portal of adi' Prospect Humbu" Formation (if) Mine dump Scale JOlperold 0E"'='=="'='~3::==':;O.OO feet .~"",=,====="",=,==="",=,===3o.5 km N Silicifi.d rock. 1 Explosive breccia Topo!':l'aphic baBe modi tied rrom tb .. 1968 USGS Mercur, Ut""" topo!':l'apblcauadraJI..II:1e Figure F i g u r e 4. 4, Geologie map G eologic m a p of o f Mercur, Mercur, Utah. Utah, 14 14 the t h e Ophir O p h i r anticline. anticline. It I t is i s bbelieved e l i e v e d to t o have h a v e resulted resulted from f r o m further f u r t h e r compression c o m p r e s s i o n of o f tthe h e area a r e a following f o l l o w i n g the the fform~tion o r m a t i o n of o f tthe h e Ophir O p h i r anticline. anticline. The T h e Eagle E a g l e Hill H i l l intrusive i n t r u s i v e definitely d e f i n i t e l y cuts c u t s the t h e Great Great Blue B l u e Limestone L i m e s t o n e sequence s e q u e n c e and a n d apparently a p p a r e n t l y has h a s caused c a u s e d some some drag d r a g folds f o l d s nnear e a r it. it. It I t appears a p p e a r s to t o be b e a large l a r g e intrusive intrusive dike d i k e that t h a t could c o u l d once o n c e have h a v e served s e r v e d as a s a conduit c o n d u i t ffor o r aa fissure f i s s u r e eruption. eruption. i n the t h e map map in 0 The W T h e trend t r e n d of o f the t h e intrusive i n t r u s i v e is is N N 75 75°W a r e a with w i t h the t h e general g e n e r a l trend t r e n d off o f f the t h e map m a p to to area o t h e west w e s t being b e i n g about about N 90°W the N 90 w., Normal, N o r m a l , reverse, r e v e r s e , and a n d strike-slip s t r i k e - s l i p faults f a u l t s occur o c c u r in i n the the m a p area. area. map A l l faults f a u l t s observed o b s e r v e d in i n tthe h e gold g o l d ore o r e sequence sequence All displace d i s p l a c e tthe h e altered a l t e r e d rock r o c k and a n d appear a p p e a r to t o have h a v e formed formed after a f t e r silicification, s i l i c i f i c a t i o n , although a l t h o u g h there t h e r e could c o u l d have h a v e been been movement rrenewed enewed m o v e m e n t after a f t e r silicification. silicification. Most M o s t of o f the the f a u l t s appear a p p e a r to t o be b e nnormal, o r m a l , bbut u t several s e v e r a l of o f the t h e low-angle low-angle faults f a u l t s appeqr a p p e a r to t o be b e reverse. reverse, faults S p u r r (1894-95) ( 1 8 9 4 - 9 5 ) mentioned mentioned Spurr t h a t some s o m e of o f the t h e gold g o l d deposits d e p o s i t s occur o c c u r along a l o n g small s m a l l faults. faults. that S o m e of o f the t h e faults f a u l t s show s h o w several s e v e r a l pperiods e r i o d s of o f displacemento displacement. Some S l i c k e n s i d e s on o n a low-angle l o w - a n g l e fault f a u l t above a b o v e the t h e faulted faulted Slickensides b l o c k of o f jjasperoid a s p e r o i d near n e a r the t h e central c e n t r a l part p a r t of o f the t h e GeyserGeyserblock M a r i o n mine m i n e show s h o w a prominent p r o m i n e n t reverse r e v e r s e direction d i r e c t i o n of o f movement, movement, Marion b u t movement m o v e m e n t probably p r o b a b l y occurred o c c u r r e d in i n both b o t h directions. directions. but This This l o w - a n g l e fault f a u l t is i s cut c u t and a n d offset o f f s e t a ffew e w inches i n c h e s by b y a high high low-angle a n g l e fault. fault. angle s m a l l faults faults w h i c h occur o c c u r on o n opposite opposite Two small which s i d e s of o f the t h e bbreccia r e c c i a in i n the t h e Sacramento S a c r a m e n t o mine m i n e area a r e a clearly clearly sides 15 15 extend e x t e n d a short s h o r t distance d i s t a n c e into i n t o the t h e iintrusive. ntrusive. \ The T h e one o n e on on t h e south s o u t h side s i d e of o f the t h e ppipe i p e has has a a red r e d hematite-stained hematite-stained the f r a c t u r e zzone one w h i c h is is m o r e silicified s i l i c i f l e d than t h a n normal normal fracture which more f o r this t h i s part p a r t of o f the t h e altered a l t e r e d intrusive. intrusive. for tthe h e nnorth o r t h side s i d e of o f tthe h e ppipe i p e has has a a larger larger T h e fault f a u l t on on The vertical vertical d i s p l a c e m e n t than t h a n tthe h e one o n e on o n the t h e south s o u t h side. side. displacement The T h e bbreccia r e c c i a that t h a t occurs o c c u r s near n e a r the t h e center c e n t e r of o f the t h e old old ttown o w n of o f Mercur M e r c u r on o n the t h e SE side s i d e of o f the the Geyser-Marion Geyser-Marion mine m i n e occurs o c c u r s approximately a p p r o x i m a t e l y at a t the t h e intersection i n t e r s e c t i o n of of f a u l t s (Fig. ( P i g . 5). 5)• faults two two O n e of o f the t h e faults f a u l t s appears a p p e a r s to t o extend extend One d o w n from f r o m the t h e graben g r a b e n which w h i c h forms f o r m s the the w e s t e r n boundary b o u n d a r y of of down western the B r i c k y a r d mine. mine* the Brickyard T h e bbreccia r e c c i a is i s not n o t silicified silicifled The a n d therefore t h e r e f o r e pprobably r o b a b l y formed f o r m e d after a f t e r the t h e hydrothermal hydrothermal and a c t i v i t y in i n the t h e area. area. activity T h e bbreccia r e c c i a was w a s mined m i n e d for f o r gold gold The bbut u t tthe h e uunaltered n a l t e r e d ssedimentary e d i m e n t a r y sequence s e q u e n c e in i n contact contact tthe h e breccia b r e c c i a was w a s not n o t mined m i n e d which w h i c h ssuggests u g g e s t s tthat hat with with mineralized mineralized material w a s on o n the t h e down d o w n faulted f a u l t e d side s i d e or o r fell f e l l into i n t o an an material was o p e n area. area. open The m a t e r i a l aabutting b u t t i n g the t h e fault f a u l t nnear e a r the the The material B r i c k y a r d mine m i n e appears a p p e a r s tto o bbe e uunsorted n s o r t e d alluvium, alluvium, Brickyard whereas whereas t h e material m a t e r i a l bbelow e l o w tthe h e Geyser-Marion G e y s e r - M a r i o n mine m i n e is is a a breccia. breccia. the T h e breccia b r e c c i a could c o u l d have h a v e resulted r e s u l t e d from f r o m extension e x t e n s i o n of o f the the The f a u l t zone z o n e and a n d repeated r e p e a t e d uup p and a n d down down m o v e m e n t of o f the the fault movement f a u l t , or o r from f r o m the t h e formation f o r m a t i o n of o f a solution s o l u t i o n cave c a v e in i n the the fault, f a u l t zone z o n e and a n d collapse c o l l a p s e oof f the t h e roof. roof. fault 16 16 Figure Collapse F i g u r e 5. 5» C o l l a p s e bbreccia r e c c i a on o n east e a s t side s i d e of o f tthe h e GeyserGeyserMarion M a r i o n mine m i n e showing s h o w i n g old o l d mine m i n e workings. workings. Brecc B r e c c iia a Pipes Pipes One most O n e of o f the the m o s t noticeable n o t i c e a b l e breccias b r e c c i a s in i n tthe h e Mercur Mercur area mine a r e a occurs o c c u r s at a t the t h e Sacramento Sacramento m i n e (Fig. ( F i g . 6). 6). It I t appears appears tto o bbe e an a n explosive e x p l o s i v e bbreccia r e c c i a ppipe i p e that t h a t resulted r e s u l t e d from f r o m aa rrelease e l e a s e of o f bbuilt-up u i l t - u p gas g a s pressure. pressure. The T h e pipe p i p e occurs occurs at a t the t h e contqct c o n t a c t between b e t w e e n the t h e intrusive i n t r u s i v e aand n d the t h e Great G r e a t Blue Blue Limestone. Limestone. The T h e bbreccia r e c c i a shows s h o w s a crude c r u d e zonation z o n a t i o n of o f breccia breccia ffrq~ments. ragments. On bboth On o t h edges e d g e s of o f the t h e exposed e x p o s e d pipe, pipe, the the breccia b r e c c i a is i s composed c o m p o s e d of o f angular a n g u l a r fragments f r a g m e n t s of o f 1-5 1 - 5 cm. cm, average a v e r a g e size s i z e in i n a rred, e d , fine-grained, f i n e - g r a i n e d , silicified s i l i c i f i e d (quartz (quartz and a n d chalcedony) c h a l c e d o n y ) groundmass g r o u n d m a s s (Fig. ( F i g , 7). 7)» In I n the t h e central c e n t r a l portion portion of o f the t h e ppipe, i p e , tthe h e breccia b r e c c i a is i s composed c o m p o s e d of o f mostly m o s t l y angular angular fragments f r a g m e n t s and a n d blocks b l o c k s in i n aa rred, e d , fine-grained f i n e - g r a i n e d silicified silicified (quartz ( q u a r t z and a n d chalcedony) c h a l c e d o n y ) groundmass. groundmass. A A large l a r g e mass m a s s of of silicified s i l i c i f i e d rrock o c k occurs o c c u r s at a t the t h e base b a s e of o f the t h e pipe p i p e exposure exposure 17 F i g u r e 66.. V i e w oof f Sacramento S a c r a m e n t o mine m i n e aarea rea M e r c u r , Utah. Utah. Figure View Mercur, ((l) 1 ) altered altered E agle H i l l rrhyollte, h y o l i t e , ((2) 2 ) Sacramento Sacramento Eagle HlII bbreccIa r e c c i a ppIpe, i p e , ((J) 3 ) cc a.. rrbon-rich b o n - r i c h aare r e a.., , ((4) 4 ) old old bbu u iildings ldings a a nnd d adit a d i t llocations o c a t i o n s ffor o r tthe h e Sacramento Sacramento m ine mine FFlgure i g u r e 77, . C l o s e - u p oof f ttypical y p i c a l bbreccia r e c c i a ffound o u n d nnea e a rr Close-up eedge d g e oof f tthe h e SSac a c rramento a m e n t o bbreccia r e c c i a pipe. pipe. the the 1~ 18 and a n d similar s i m i l a r ffragments r a g m e n t s occur o c c u r in i n tthe h e groundmass g r o u n d m a s s above. above. ~he The mass which m a s s contains c o n t a i n s rare r a r e quartz q u a r t z pphenocrysts henocrysts w h i c h suggest suggest that t h a t tthis h i s rrock o c k is i s aan n intrusive i n t r u s i v e that t h a t invaded i n v a d e d tthe h e breccia breccia after a f t e r ppipe i p e formation. formation. The mass T h e llarge arge m a s s could c o u l d also a l s o represent represent a lRrge l a r g e block b l o c k of o f altered a l t e r e d intrusive i n t r u s i v e included i n c l u d e d in i n the the bbreccia. reccia. T h e eentire n t i r e ppipe i p e hhas a s bbeen e e n altered a l t e r e d tto o aa siliceous siliceous ~he s i n t e r which w h i c h adds a d d s tto o tthe h e ddifficulty i f f i c u l t y of o f iidentifying d e n t i f y i n g the the sinter l l t h o l o g y of o f the t h e rrock o c k fragments. fragments. lithology A i g h aangle n g l e fault fault A hhigh oof f small s m a l l displacement d i s p l a c e m e n t cuts c u t s the t h e ppipe. ipe. T h i s fault f a u l t might might This bbe e due d u e tto o stresses s t r e s s e s directed d i r e c t e d uupwards p w a r d s and a n d sidewards s i d e w a r d s caused caused b y renewed r e n e w e d ppost-consolidation ost-consolidation m o v e m e n t oof f tthe h e intrusive intrusive by movement a f t e r ppipe i p e fformation. ormation. after A a r r o w hhighly i g h l y fractured, fractured, A nnarrow s l l c k e n s i d e d zzone one w a s observed o b s e r v e d in i n tthe he m i n e d area a r e a around around slickensided was mined tthe h e pipe. pipe. The T h e only o n l y previous p r e v i o u s description d e s c r i p t i o n oof f tthis h i s area a r e a is i s given given by b y Lenzi L e n z l (1971. ( 1 9 7 1 , pp.. 2). 2). To Mercur, T o tthe h e south. s o u t h , above above M e r c u r , are a r e several s e v e r a l open o p e n cuts cuts along mountain with a l o n g tthe he m ountain w i t h oone n e vvery e r y llarge a r g e open o p e n slope slope that t h a t exposes e x p o s e s tthe h e contact c o n t a c t of o f intrusive i n t r u s i v e rrhyolite h y o l i t e with with the The t h e limestone l i m e s t o n e country c o u n t r y rrock. ock. T h e llimestone i m e s t o n e has has bbeen e e n altered a l t e r e d tto o a light l i g h t violet v i o l e t aand n d red r e d color c o l o r near near the t h e intrusive. i n t r u s i v e , otherwise o t h e r w i s e the t h e a~lteration l t e r a t i o n appears appears a s light light b u f f , silicified s i l i c i f i e d llimestone i m e s t o n e or o r light-gray-to light-gray-to as buff, w h i t e silicified s i l i c i f i e d shales s h a l e s o. white IIn n contrast, contrast, the t h e exposure e x p o s u r e appears a p p e a r s tto o bbe e a hhighly i g h l y brecciated brecciated zone z o n e aand n d nnot o t a contact c o n t a c t zzone o n e of o f vviolet i o l e t tto o red r e d altered a l t e r e d limestor.e. limestone. One wast O n e other o t h e r explosive e x p l o s i v e bbreccia r e c c i a ppipe i p e occurs occurs w a s t of o f the the Sacramento S a c r a m e n t o bbreccia r e c c i a pipe. pipe. The Mercur The M e r c u r South S o u t h bbreccia r e c c i a pipe pipe iis s similar s i m i l a r tto o tthe h e Sacramento S a c r a m e n t o bbreccia r e c c i a ppipe i p e except e x c e p t that that 19 19 iit t lacks l a c k s tthe h e red r e d color c o l o r of o f tthe h e ggroundmass. roundmass. There T h e r e is i s aa r a d i a t i n g fault f a u l t ppattern a t t e r n on o n tthe h e south s o u t h side s i d e of o f tthe h e pipe pipe radiating b u t no n o zonation z o n a t i o n of o f the t h e bbreccia r e c c i a iis s eevident v i d e n t from f r o m the the but o u t c r o p exposure. exposure. outcrop T h e rock r o c k ffragments r a g m e n t s aand nd The groundmass groundmass iin n the t h e ppipe i p e are a r e silicified s i l i c i f i e d to t o a siliceous s i l i c e o u s ssinter. inter. One One r o c k fragment f r a g m e n t from f r o m this t h i s ppipe ipe w h i c h was w a s bbelieved e l i e v e d tto o be be rock which aan n iintrusive n t r u s i v e fragment fragment w h e n aanalyzed n a l y z e d bby y X-ray X-ray when diffraction diffraction s h o w e d the t h e ppresence r e s e n c e of o f quartz q u a r t z aand n d sanidine. sanidine. showed Features F e a t u r e s suggesting s u g g e s t i n g iincipient n c i p i e n t bbreccia r e c c i a ppipe ipe occur Mercur o c c u r tto o tthe h e east e a s t of o f tthe he M e r c u r South S o u t h ppipe. ipe. formation formation Here H ere slight slight s i l i c i f i c a t i o n similar s i m i l a r tto o tthat h a t oof f tthe h e other o t h e r two t w o pipes pipes silicification o c c u r s at a t the t h e intersection i n t e r s e c t i o n oof f ttwo w o faults. faults. occurs Jumbled Jumbled s t r a t a exposed e x p o s e d tto o tthe h e east e a s t iin n aa road r o a d ccut u t ((not n o t shown s h o w n on on strata F i g . 4) 4) m i g h t bbe e due d u e tto o faulting, f a u l t i n g , slump, s l u m p , or o r possibly possibly Fig. might bbreccia r e c c i a ppipe i p e formation formation processes. processes. Joint J o i n t Patterns Patterns Too determine T d e t e r m i n e ppast a s t stresses s t r e s s e s iin n tthe h e area, area, 129 1 2 9 joint joint attitudes w ere m e a s u r e d iin n tthe he M e r c u r area a r e a primarily primarily attitudes were measured Mercur i n the t h e Geyser-Marion G e y s e r - M a r i o n and a n d Mercur M e r c u r Hill H i l l aareas r e a s and a n d were were in ccontoured o n t o u r e d to t o give give F i g u r e 8. 8. Figure F igure 9 9 shows s h o w s the the Figure plot plot o f the t h e strike s t r i k e ddirections i r e c t i o n s of o f tthe h e 129 1 2 9 jjoints o i n t s uused s e d for for of F i g u r e 8; 8; F i g u r e 10 1 0 shows s h o w s tthe h e pplot l o t of o f tthe h e strike s t r i k e directions directions Figure Figure o f 71 ? 1 faults f a u l t s on o n the t h e included i n c l u d e d ggeologic eologic m a p ((Fig. F i g . 4). 4). of map o F i g u r e 10 1 0 sshows h o w s a ggeneral eneral N s t r i k e of of m a n y of of Figure N 6600 ° EE strike many tthe h e faults; faults; the t h e strikes s t r i k e s of o f the t h e jjoints o i n t s hhave a v e a concentration concentration 20 N w E s F i g u r e 88.. C o n t oour u r ddlagram i a g r a m (lower ( l o w e r hemisphere h e m i s p h e r e project1on) projection) F1gure Cont oo ff jjo1nt o i n t dens1ty d e n s i t y oof f 129 1 2 9 jjo1nts o i n t s 1n i n tthe h e Mercur. Mercur, U a h area. area. Utt ah 21 21 N N o0 W 90 L..-..-----~~~22~:.::.L---_.l90 E Figure F i g u r e 9. 9. Plot P l o t oof f strike s t r i k e directions d i r e c t i o n s of o f 129 1 2 9 joints. joints. N o W 90 L -_ _ _ _ _ -=:::::SWI~~~L_ _ _ ___.J 90 E Figure Plot F i g u r e 10. 10. P l o t of o f strike s t r i k e directions d i r e c t i o n s of o f 71 ?1 faults faults at Mercur. Utah. at Mercur, Utah. 222 2 at N 50 E which a t about about N 5 0 °0 E w h i c h is i s in i n comparative c o m p a r a t i v e agreement a g r e e m e n t with with the t h e fault f a u l t directions. directions. This T h i s direction d i r e c t i o n is i s approximately approximately perpendicular p e r p e n d i c u l a r to t o the t h e axial a x i a l plane. p l a n e oof f tthe h e Ophir O p h i r anticline anticline which w h i c h would w o u l d make m a k e this t h i s the t h e pprobable r o b a b l e tension tension direction. direction. This T h i s direction d i r e c t i o n is i s verI v e r y similar s i m i l a r to t o the t h e ttrend r e n d of o f tthe h e line line 0 connecting B)) w which c o n n e c t i n g the t h e ttwo w o bbreccia r e c c i a pipes p i p e s (5' ( N 55 55°B h i c h might might indicate I n d i c a t e a structural s t r u c t u r a l control c o n t r o l for f o r their t h e i r formation. formation. Two faults mine f a u l t s show s h o w extension e x t e n s i o n inin the t h e Mercur M e r c u r lfill M i l m i n e area area bbut u t only o n l y one o n e correlates c o r r e l a t e s with w i t h tthe h e tension tension direction. direction. This might This m i g h t indicate i n d i c a t e that t h a t other o t h e r stress s t r e s s fields f i e l d s existed existed • oo in the past. The N 40 V minor concentration on the in the past. The N 40 W minor concentration on the fault plot is believed to be the release joint and fault fault plot is believed to be direction. The N 25°E and to be the shear directions. to be the is about to the the release joint and fault The N 25 0 E and N 80°8 directions are believed direction. shear N 80°B d i r e c t i o n s are believed The trend of the intrusive directions. The trend of the intrusive is about N 7S o V in the map Iirea with the general trend N 75°W i n the map a r e a with the general trend to the west of the map area being about B-V which is west of the map a r e a being about B-W w h i c h is directions. However, it similar to one of the shear directions. similar to one of the shear that the intrusive However, it is not clear that the intrusive came in along the shear is not clear direction. came in along the shear direction. The general sequence of events for this area is The g e n e r a l sequence of events for this area is believed to have started with compression to form the believed to have started with c o m p r e s s i o n t o form t h e ~illull (1932, p. faulting. Gilluly (1932, p . Ophir anticline with some faulting. 91) Ophir 91) anticline with some believed the compression occurred in Late Cretaceous believed or early Tertiary time. the compression The intrusion of the Eagle Hill occurred in Late or early Tertiary time. The rhyolite followed the intrusion of Cretaceous the Eagle rhyolite followed the formation of the anticline and formation of the anticline Hill and disrupted the general anticlinal trends, but occurred disrupted the general anticlinal trends, but occurred 23 23 while w h i l e tthe h e area a r e a was w a s still s t i l l in i n compression. compression. Further Further ccompression o m p r e s s i o n of o f tthe h e area a r e a caused c a u s e d new n e w and a n d renewed r e n e w e d faulting. faulting. T h i s sequence s e q u e n c e is i s similar s i m i l a r to t o that t h a t given g i v e n by b y Gilluly Gilluly This e x c e p t that t h a t tthe h e author a u t h o r bbelieves e l i e v e s the t h e area area w a s in i n aa except was c o n t i n u a l state s t a t e of o f compression c o m p r e s s i o n during d u r i n g the t h e sequence s e q u e n c e of of continual events. events. B e c a u s e only o n l y one o n e set s e t of o f stress s t r e s s directions directions Because is is r e a d i l y apparent a p p a r e n t this this w o u l d tend t e n d to t o indicate i n d i c a t e one one readily would m a j o r stress s t r e s s field. field. major G i l l u l y (1932, ( 1 9 3 2 , pp.. 91) 9 1 ) bbelieved e l i e v e d that that Gilluly t h e igneous i g n e o u s intrusions i n t r u s i o n s occurred o c c u r r e d in i n Eocene E o c e n e time. time. the Moore Moore ( 1 9 7 3 . p. p . 99) 9 9 ) gives g i v e s a bbiotite iotite K - A r age a g e date d a t e of o f 31.6 31.6 ± + 0.9 0.9 (1973. K-Ar m .y. m.y. ( O l i g o c e n e ) for f o r the t h e Eagle E a g l e Hill H i l l rhyolite r h y o l i t e in i n the the (Oligocene) Sacramento Sacr~mento m i n e area a r e a at a t Mercur. Mercur. mine I N T R U S I V E ROCKS ROCKS iNTRUSIVE Figure F i g u r e 11 1 1 sshows h o w s tthe h e general g e n e r a l ddistribution i s t r i b u t i o n oof f intrusive intrusive igneous I g n e o u s rrocks o c k s iin n the t h e ssouthern o u t h e r n Oquirrh O q u i r r h Mountains M o u n t a i n s (Gilluly, (Gilluly, 1932. 1 9 3 2 , pplate l a t e 13. 1 3 , pp.. 97). 97). rrocks ocks The T h e vvarieties a r i e t i e s oof f igneous igneous include I n c l u d e rrhyolite h y o l i t e pporphyry o r p h y r y (Eagle ( E a g l e Hill H i l l rhyolite). rhyolite), llamprophyre amprophyre (kersantite), ( k e r s a n t i t e ) , and a n d granodiorite g r a n o d i o r i t e porphyry porphyry (Bird's-eye ( B i r d ' s - e y e porphyry). porphyry), Kersantite K ersantite Gilluly G i l l u l y (1932. ( 1 9 3 2 , pp.. 663) 3) found f o u n d ffour o u r lamprophyre lamprophyre Canyon. ((kers~ntite) k e r s a n t i t e ) dikes d i k e s outcropping o u t c r o p p i n g in i n Ophir Ophir C anyon, The The author a u t h o r hhas a s collected c o l l e c t e d some s o m e of o f tthe h e llamprophyre a m p r o p h y r e ffrom r o m the the e a s t side s i d e of of H a r t m a n n Gulch G u l c h and a n d hhas a s found f o u n d small s m a l l amounts amounts e'3.st Hartmann o f ppyrite y r i t e ppresent r e s e n t iin n the t h e rrock. ock. of ((1932. 1932, IIt t is i s altered a l t e r e d aas s Gilluly Gilluly p . 64) 6 4 ) has h a s stated. stated. p. Bird's-eye B i r d ' s - e y e Porphyry Porphyry The The B B'ird' i r d ' ss-eye - e y e pporphyr;r. o r p h y r y , nnamed a m e d bby y Spurr S p u r r (1894-95, (1894-95, p . 379). 3 7 9 ) # outcrops o u t c r o p s on on P o r p h y r y Hill, H i l l , Porphyry Porphyry K n o b , and and p. Porphyry Knob, L i o n Hill. Hill. Lion G i l l u l y (1932, ( 1 9 3 2 , pp.. 50) 5 0 ) cclassified l a s s i f i e d it i t as a s aa Gllluly granodiorite g r a n o d i o r i t e porphyry. porphyry. The T h e aauthor u t h o r hhas a s examined examined of o f it i t oon n P Porphyry orphyry K Knob n o b and and P Porphyry orphyry H Hill. ill. exposures exposures The T h e groundmass groundmass o f tthe he B i r d ' s - e y e pporphyry o r p h y r y on on P orphyry K n o b is i s noticeably noticeably of Bird's-eye Porphyry Knob ppropylitlzed r o p y l i t i z e d and and w eathered. weathered. G i l l u l y ((1932, 1 9 3 2 , pp.. 449) 9 ) found found Gilluly iit t to t o contain c o n t a i n pphenocrysts h e n o c r y s t s of o f pplagioclase lagioclase (Ab^Q-An^Q), (Ab60-An40)' b a r r e l shaped. s h a p e d , hhexagonal e x a g o n a l bbiotite l o t l t e ttablets, a b l e t s , hornblende. hornblende, barrel 25 ... O~)I ( .n)lOn • ! ! ,,-/ ( i ., ' \ \ I'tinnt N 1 Sel l. .;..~~~~'===",;2 .. li n "- , I map FFigu i g u rre e 111. 1. IIndex ndex m a p sshow h o w iing n g tthe h e ggene e n e rral a l distr d i s t ribut i b u tion ion of igneo us rocks o f i g n e o u s r o c k s iin n tthe h e ssouth o u t h ee rrn n O q u irrh i r r h Mou M o u ntain n t a i n s. s. Oqu 26 26 minor m inor orthoclase, o r t h o c l a s e , and a n d quartz. quartz. Eagle E a g l e Hill H i l l Rhyolite Rhyolite The T h e Eagle E a g l e Hill H i l l rhyolite r h y o l i t e Was w a s nnamed a m e d bby y Spurr S p u r r (1894-95. (1894-95, pp.. 377) 377) for f o r tthe h e rrhyolite h y o l i t e pporphyry o r p h y r y that t h a t crops c r o p s out o u t on on Eagle tthe h e north n o r t h side s i d e of of E a g l e Hill. Hill. The T h e intrusive i n t r u s i v e rhyolite rhyolite pporphyries o r p h y r i e s at a t Ophir O p h i r and a n d Mercur M e r c u r hhave a v e bbeen e e n given g i v e n the the name n a m e and a n d are a r e somewhat s o m e w h a t similar s i m i l a r mineralogically. mineralogically• ooutcrops u t c r o p s of o f tthe h e rhyolite r h y o l i t e examined e x a m i n e d were w e r e intrusive intrusive same same All All in in character* character. Structural S t r u c t u r a l Relations Relations Exposures Eagle were E x p o s u r e s of of E a g l e Hill H i l l rhyolite rhyolite w e r e examined e x a m i n e d in in tthe h e Ophir O p h i r area a r e a in i n Dry D r y Canyon C a n y o n and a n d oon n the t h e north n o r t h side side Ophir O p h i r Canyon. Canyon. of of The T h e rhyolite r h y o l i t e porphyry p o r p h y r y hhas a s tthe h e fform o r m of o f aa dike d i k e in i n Ophir O p h i r Canyon C a n y o n and a n d hhas a s a narrow n a r r o w contact c o n t a c t zone. zone. In In the Dry the D r y Canyon C a n y o n area a r e a above a b o v e Ophir O p h i r several s e v e r a l intrusive i n t r u s i v e masses masses of o f rrhyolite h y o l i t e occur. occur. Gilluly G i l l u l y (1932, ( 1 9 3 2 , pp.. 58) 5 8 ) described described .- several s e v e r a l outcrops o u t c r o p s of o f rrhyolite h y o l i t e breccia b r e c c i a in i n tthe h e Dry D r y Canyon Canyon area. area. The T h e author a u t h o r examined e x a m i n e d tthe h e one o n e above a b o v e the t h e Hidden Hidden T reasure Treasure mine. mine. Two small which s m a l l outcrops o u t c r o p s of o f rhyolite r h y o l i t e pporphyry orphyry w h i c h have have been NNE of b e e n previously p r e v i o u s l y overlooked o v e r l o o k e d occur o c c u r NNE o f tthe h e old old townsite t o w n s i t e of o f West W e s t Mercur. Mercur. outcrops outcrops The T h e southernmost s o u t h e r n m o s t of o f these these of o f rrhyolite h y o l i t e exhibits e x h i b i t s characteristics c h a r a c t e r i s t i c s of o f both b o t h aa sill s i l l and a n d a dike. dike. An adit An a d i t bblasted l a s t e d into i n t o tthe he intrusive intrusive 27 eexposes x p o s e s a ~ouge g o u g e zone z o n e at a t the t h e contact c o n t a c t between b e t w e e n the t h e limestone limestone and a n d the t h e iintrusive. ntrusive. Pieces P i e c e s of o f bbreccia r e c c i a containing c o n t a i n i n g limestone limestone and a n d intrusive i n t r u s i v e can c a n be b e found f o u n d on o n the t h e outcrop o u t c r o p aand n d appeqr a p p e a r to to bbe e an a n intrusive i n t r u s i v e bbreccia. reccia. The T h e intrusive i n t r u s i v e is i s believed b e l i e v e d to to have h a v e bbeen e e n emplaced e m p l a c e d as a s a vviscous, i s c o u s , dry d r y magma. magma. Alignment Alignment o f bbiotite i o t i t e flakes f l a k e s is i s apparent a p p a r e n t which w h i c h suggests s u g g e s t s injection injection of o f a vviscous i s c o u s magma. magma. of The T h e nnorthern o r t h e r n of o f tthe h e two t w o outcrops o u t c r o p s is i s best b e s t exposed exposed iin n an a n exploration e x p l o r a t i o n ppit i t and a n d is i s a bbreccia r e c c i a of o f limestone limestone and a n d rhyolite r h y o l i t e fragments. fragments. The T h e breccia b r e c c i a is I s believed b e l i e v e d also also tto o bbe e an a n iintrusive n t r u s i v e bbreccia. reccia. T h e lack l a c k of o f hydrothermal hydrothermal The a l t e r a t i o n of o f tthe h e limestone l i m e s t o n e or o r the t h e intrusive i n t r u s i v e fragments fragments alteration and a n d the t h e small s m a l l contact c o n t a c t zone z o n e is i s indicative i n d i c a t i v e of o f a hot, h o t , dry dry magma. m agma. These T h e s e exposures e x p o s u r e s are a r e important i m p o r t a n t because b e c a u s e they they a r e bbelieved e l i e v e d to t o represent r e p r e s e n t a rrelatively e l a t i v e l y unaltered u n a l t e r e d exposure exposure are o f intrusive i n t r u s i v e similar s i m i l a r tto o that t h a t exposed e x p o s e d on o n the t h e nnorth o r t h side s i d e of of of E a g l e Hill. Hill. Eagle ~he T h e rhyolite r h y o l i t e that t h a t outcrops o u t c r o p s at a t the t h e mouth m o u t h of o f Mercur Mercur Canyon C a n y o n hhas a s the t h e form f o r m of o f a dike. dike. The T h e structural s t r u c t u r a l character c h a r a c t e r for f o r the t h e Eagle E a g l e Hill H i l l rhyolite rhyolite on o n the t h e north n o r t h side s i d e of o f Eagle E a g l e Hill H i l l is i s a llarge a r g e dike d i k e which which hhas a s bbeen e e n forcibly f o r c i b l y injected. injected. In I n most m o s t pplaces l a c e s only o n l y aa narrow n a r r o w contact c o n t a c t zone z o n e exists e x i s t s bbut u t in i n several s e v e r a l places places s i l i c i f i e d zones z o n e s rranging a n g i n g uup p to t o several s e v e r a l tens t e n s of o f feet f e e t occur. occur. silicified In mine, I n tthe h e quarried q u a r r i e d area a r e a at a t the t h e Sacramento Sacramento m i n e , mining mining o p e r a t i o n s exposed e x p o s e d tthe h e contact c o n t a c t zone z o n e which w h i c h is i s convex c o n v e x outward. outward. operations 228 8 Petrology Petrology The Ophir T h e rhyolite r h y o l i t e examined e x a m i n e d iin n tthe he O p h i r a~rea r e a is is a porphyry porphyry ccont~inlng o n t a i n i n g about a b o u t 7-10% 7 - 1 0 # visible v i s i b l e quartz q u a r t z pphenocrysts. henocrysts. ss~nidine, anidine, oligocl~se, oligoclase, sericite, s e r i c i t e , apatite, a p a t i t e , calcite, calcite, opaques o p a q u e s qre a r e visible v i s i b l e in i n tthin h i n section. section. aphanitic. aphanitic, Quartz, Quartz, ~nd and The T h e ggroundmass roundmass is is K-feldspar K - f e l d s p a r staining s t a i n i n g sshowed h o w e d tthe h e ggroundmass r o u n d m a s s to to consist c o n s i s t of o f sanidine s a n i d i n e and a n d quartz. quartz. The T h e sanidine s a n i d i n e and and with white pplagioclase l a g i o c l a s e bblend lend w i t h tthe he w h i t e ggroundrnass r o u n d m a s s in i n hhand a n d specimen.· specimen. No bbiotite iotite w a s seen s e e n in i n the t h e exposures e x p o s u r e s or o r iin n tthin h i n section. section. was No m agnetite w a s seen s e e n bby y tthe h e author a u t h o r although a l t h o u g h it i t was was m~gnetite was d e s c r i b e d bby y Gilluly G i l l u l y (1932, ( 1 9 3 2 , pp.. 559). 9). described P y r i t e is i s present. present. Pyrite Sanidine S a n i d i n e occurs o c c u r s as a s pphenocrysts h e n o c r y s t s and a n d is i s tthe h e dominant dominant f e l d s p a r present. present. feldspar O l i g o c l a s e is i s more m o r e abundant a b u n d a n t in i n the the Oligoclase i n t r u s i v e at a t Ophir O p h i r than t h a n iin n the t h e rrhyolite h y o l i t e at a t Mprcur, Mercur, intrusive a l t h o u g h only o n l y a few f e w thin t h i n sections s e c t i o n s oof f tthe h e rrhyolite h y o l i t e at at although Ophir w e r e studied. studied. Ophir were The West The W e s t Mercur M e r c u r intrusive i n t r u s i v e ccontains o n t a i n s abundant a b u n d a n t biotite biotite and a n d quartz q u a r t z pphenocrysts h e n o c r y s t s which w h i c h comprise c o m p r i s e about a b o u t 7-10% 7 - 1 0 $ of o f the the rock. rock. Quartz, Q u a r t z , sanidine, s a n i d i n e , oligoclase, o l i g o c l a s e , bbiotite, i o t i t e , sericite, sericite, and a n d c~lcite c a l c i t e are a r e visible v i s i b l e iin n tthin h i n section. section. Quartz, Q uartz, sanidine, sanidine, a n d bbiotite i o t i t e are a r e tthe he m o s t abundant abundant m i n e r a l s — c a l c i t e is is and most minerals--calcite also a l s o abundant. abundant. The T h e groundmass g r o u n d m a s s is i s aphgnitic. aphanitic. mouth Mercur IIn n tthe h e dike d i k e aat t tthe he m o u t h of of M e r c u r Canyon, C a n y o n , quartz, quartz, sanidine, s a n i d i n e , ppla~ioclase, l a g i o c l a s e , calcite, c a l c i t e , and a n d sericite s e r i c i t e are a r e visible visible i n thin t h i n section. section. in T h e groundmass g r o u n d m a s s is i s aphanitic. aphanitic. The Small Small 29 29 spherulites s p h e r u l i t e s of o f what w h a t ~re a r e either e i t h e r quartz q u a r t z or o r kaolinite kaolinite are a r e ppresent. resent. Quartz Q u a r t z aand n d sanidine s a n i d i n e are a r e tthe h e ttwo w o most most abundant a b u n d a n t minerals m i n e r a l s present--calcite p r e s e n t — c a l c i t e is i s locally l o c a l l y abundant. abundant. Kaolinite w a s identified i d e n t i f i e d bby y X-ray X - r a y diffraction. diffraction. Kaolinite was Some Some bbiotite iotite w a s found f o u n d on o n study s t u d y of o f tthe h e outcrop o u t c r o p exposure. exposure. was Small Small a m o u n t s of o f pyrite p y r i t e are a r e visible v i s i b l e in i n polished p o l i s h e d section. section. amounts In I n the t h e Eagle E a g l e Hill H i l l rhyolite r h y o l i t e at a t Mercur, M e r c u r , quartz. q u a r t z , sanidine, sanidine, oligoclase, o l i g o c l a s e , bbiotite, i o t i t e , sericite. s e r i c i t e , calcite, c a l c i t e , and a n d opaques o p a q u e s are are vvisible isible in i n tthin h i n section. section. The T h e opaques o p a q u e s in i n tthin h i n section section in i n reflected r e f l e c t e d light l i g h t appear a p p e a r to t o bbe e pyrite. pyrite. haolinite Kaolinite is i s ppresent r e s e n t in i n small s m a l l amounts a m o u n t s throughout t h r o u g h o u t the t h e intrusive intrusive and a n d is i s abundant a b u n d a n t in i n tthe h e intrusive i n t r u s i v e near n e a r the t h e Sacramento Sacramento bbreccia r e c c i a ppipe. ipe. It X-ray I t was w a s identified i d e n t i f i e d by by X - r a y diffraction. diffraction. Scattered S c a t t e r e d small s m a l l amounts a m o u n t s of o f illite, i l l i t e , also a l s o identified identified bby y X-ray X - r a y diffraction, d i f f r a c t i o n , appear a p p e a r to t o be b e present p r e s e n t in i n the t h e intrusive. intrusive. Calcite, w h i c h is i s pprobably r o b a b l y hydrothermal, h y d r o t h e r m a l , is i s abundant abundant Calcite, which l o c a l l y iin n the t h e intrusive intrusive w h e r e tthere h e r e is i s a decrease d e c r e a s e in in locally where p h e n o c r y s t content. content. phenocryst C a l c i t e rreplaces e p l a c e s sanidine s a n i d i n e and and Calcite pplagioclase l a g i o c l a s e pphenocrysts h e n o c r y s t s as a s is i s evident e v i d e n t in i n thin t h i n sections. sections. T h e size s i z e of o f plagioclase p l a g i o c l a s e crystals c r y s t a l s vvaries a r i e s from f r o m phenocrysts phenocrysts The tto o microlites. microlites. S o m e of o f the" t h e pphenocrysts h e n o c r y s t s have h a v e rims r i m s of of Some quartz. quartz. A g g r e g a t e s of o f phenocrysts. p h e n o c r y s t s - (glomerophyritic (glomerophyritlc A~gregates ttexture) exture) o c c u r randomly r a n d o m l y in i n the t h e intrusive. intrusive. occur Intergrowths Intergrowths o f quartz q u a r t z and a n d feldspar f e l d s p a r occur o c c u r iin n the t h e phenocryst p h e n o c r y s t aggregates aggregates of o r occur o c c u r as a s single s i n g l e pphenocrysts h e n o c r y s t s in i n the t h e groundmass. groundmass. or The which T h e Eagle E a g l e Hill H i l l rhyolite rhyolite w h i c h outcrops o u t c r o p s at a t West West 30 30 Mercur, Mercur, Mercur, M e r c u r , and a n d Ophir, O p h i r , if i f it i t does d o e s come c o m e from f r o m one o n e lqrge large pluton, p l u t o n , pprob9bly r o b a b l y underwent u n d e r w e n t differentiation. differentiation. The T h e deposits deposits at a t Ophir O p h i r are a r e typic~l t y p i c a l mesothermal m e s o t h e r m a l deposits, d e p o s i t s , whereas whereas Mercur tthe h e deposits d e p o s i t s a~t t M e r c u r are a r e epitherm91. epithermal. Rock R o c k 91terqtion, alteration, represented r e p r e s e n t e d by b y jjasperoid. a s p e r o i d , is i s distributed d i s t r i b u t e d between b e t w e e n Ophir Ophir and a n d Mercur M e r c u r (Gilluly, ( G i l l u l y , 1932, 1 9 3 2 , pp.. 97). 97). This T h i s alteration a l t e r a t i o n could could represent r e p r e s e n t silica s i l i c a from f r o m hydrothermal h y d r o t h e r m a l solutions s o l u t i o n s coming c o m i n g from from a pluton p l u t o n at a t depth. depth. One O n e of o f the t h e distinguishing d i s t i n g u i s h i n g field field c h a r a c t e r i s t i c s bbetween e t w e e n the t h e intrusives i n t r u s i v e s at a t Ophir O p h i r and and characteristics M e r c u r is i s that t h a t the t h e Eagle E a g l e Hill H i l l rrhyolite h y o l i t e contains c o n t a i n s more m o r e biotite biotite Mercur a t Mercur M e r c u r than t h a n at a t Ophir. Ophir, at M oore Moore ( 1 9 7 3 t p. p . 100) 1 0 0 ) suggests suggests (1973, t h a t differentiation d i f f e r e n t i a t i o n from f r o m a large large m o n z o n i t i c pparent a r e n t mass mass that monzonitic u n d e r l y i n g the t h e Oquirrh O q u i r r h Mountains M o u n t a i n s gave g a v e rise r i s e to t o the t h e rhyolites rhyolites underlying a t Ophir O p h i r and a n d JVlercur, M e r c u r , Utah. Utah. a.t ALTERATION ALTERATION OF THE SEDIMENTARY HOCKS ROCKS The T h e most m o s t prominent p r o m i n e n t type t y p e of o f metamorphism m e t a m o r p h i s m oof f the the sedimentary s e d i m e n t a r y rrocks o c k s in i n the t h e Mercur M e r c u r area a r e a is i s silicification. silicification. The mined T h e silver s i l v e r ledge l e d g e from f r o m which w h i c h silver s i l v e r was was m i n e d in i n the the eearly a r l y days d a y s of o f tthe h e camp c a m p is is a typical t y p i c a l jjasperoid a s p e r o i d of o f intergrown intergrown q u a r t z grains g r a i n s and a n d where w h e r e massive m a s s i v e hhas a s little l i t t l e apparent apparent quartz permeability. permeability. T h e brecciation b r e c c i a t i o n of o f the t h e typical t y p i c a l jasperoid jasperoid The c o u l d hh~ve a v e occurred o c c u r r e d after a f t e r ore o r e deposition. deposition. could T h e gold gold The l e d g e is i s variable v a r i a b l e in in m a k e - u p as a s to t o degree d e g r e e aand n d ttype y p e of of ledge make-up alteration. alteration. C e r t a i n layers l a y e r s have h a v e been b e e n hhighly i g h l y silicified silicified Certain a n d othpr o t h e r layers l a y e r s hhave a v e quartz, q u a r t z , sericite, s e r i c i t e , illite, i l l i t e , and and qnd c a l c i t e added. a d d e d , bbut u t permeability p e r m e a b i l i t y still s t i l l exists e x i s t s iinmost n m o s t of of calcite tthe h e gold g o l d ledge ledge w h e r e silicification s i l i c i f i c a t i o n hhas a s not n o t bbeen e e n intense. intense. where T h e lack l a c k of o f ppermeability e r m e a b i l i t y in i n the the m ore m a s s i v e pportions o r t i o n s of of The more massive t h e silver s i l v e r ledge l e d g e could c o u l d explain explain w h y two t w o different d i f f e r e n t types types the why o f elemental e l e m e n t a l deposits d e p o s i t s occur. occur. of T h a t is. i s , the t h e ggold o l d bearing bearing That s o l u t i o n s did d i d nnot o t have h a v e access a c c e s s to t o the t h e silver s i l v e r lledge e d g e because because solutions o f lack l a c k of o f permeability. permeability. of T h u s the t h e silver s i l v e r ddeposited e p o s i t e d in in Thus t h e silver s i l v e r ledge l e d g e which w h i c h has h a s a hhigher i g h e r temperature t e m p e r a t u r e mineral mineral the a s s e m b l a g e than t h a n the t h e gold g o l d ledge ledge m a y bbe e earlier e a r l i e r ttha-n h a n gold gold assemblage may deposition. deposition. S p u r r (1894-95. ( 1 8 9 4 - 9 5 , p. p . 393) 3 9 3 ) mentioned m e n t i o n e d that that Spurr s m a l l amounts a m o u n t s of o f ~old g o l d occur o c c u r in i n tthe h e silver s i l v e r lledge; e d g e ; and and small l o w concentrations c o n c e n t r a t i o n s of o f silver silver w e r e found f o u n d by b y tthe h e author author low were i n the t h e gold g o l d ledge. ledge. in 32 32 Silver S i l v e r Ledge Ledge Gl11uly G i l l u l y (1932, ( 1 9 3 2 , p. p . 97-101) 9 7 - 1 0 1 ) made m a d e a thorough t h o r o u g h investigation investigation of o f the t h e jasperoids j a s p e r o i d s in i n the t h e area. area. He reports r e p o r t s that t h a t all a l l the the jasperoids j a s p e r o i d s have h a v e a thoroughly t h o r o u g h l y brecciated b r e c c i a t e d character c h a r a c t e r qnd a n d in in places p l a c e s contc:tin c o n t a i n some s o m e laminat/!d l a m i n a t e d fragments f r a g m e n t s resembling r e s e m b l i n g bedd b e d ding ing jumbled j u m b l e d at a t all a l l angles. angles. In I n some s o m e areas, a r e a s , the t h e jasperoid jasperoid appears a p p e a r s massive m a s s i v e and a n d not n o t thoroughly t h o r o u g h l y brecciated--this brecciated—this condition c o n d i t i o n is i s more m o r e common c o m m o n than t h a n one o n e is i s led l e d to t o believe b e l i e v e from from his h i s report. report. The T h e jjasperoid a s p e r o i d near n e a r the t h e old o l d Carrie C a r r i e Steele Steele workings w o r k i n g s clearly c l e a r l y transgresses t r a n s g r e s s e s bedding. bedding. Gilluly G i l l u l y found f o u n d two t w o types t y p e s of o f jasperoid j a s p e r o i d in i n the t h e 9rea a r e a of of the t h e southern s o u t h e r n Oquirrh O q u i r r h Mountalns. Mountains. One O n e that t h a t iSI is: an a n aggregate a g g r e g a t e of o f anhedral a n h e d r a l quartz q u a r t z crystals, c r y s t a l s , all a l l very very m i n u t e , usually u s u a l l y less l e s s than t h a n 0.03 0 . 0 3 milllmeter m i l l i m e t e r in in minute, d i a m e t e r , containing c o n t a i n i n g small s m a l l quantities q u a n t i t i e s of o f apatite apatite diameter, aand n d zircon z i r c o n and a n d rather r a t h e r large l a r g e quantities q u a n t i t i e s of o f blue-green, blue-green, sstron~ly t r o n g l y pleochroic p l e o c h r o i c tourmaline, tourmaline, m u s c o v i t e plates, plates, muscovite a n d caloite c a l o i t e crystals c r y s t a l s .••• . . AA second s e c o n d vvariety a r i e t y hhas a s the the and t e x t u r e known k n o w n as a s the t h e 'typical ' t y p i c a l jjasperold' asperoid texture. texture texture. IIt t consists c o n s i s t s of o f int~rgrown i n t e r g r o w n quartz q u a r t z grains grains w i t h a strong strong with ttendency e n d e n c y tto o eeuhedral u h e d r a l fforms, o r m s , sso o tthat h a t iin n tthin h i n section section m o s t oof f tthe h e grains g r a i n s aappear p p e a r bbounded o u n d e d bby y straight s t r a i g h t lines, lines, most aand n d nnumerous u m e r o u s hhexagonal e x a g o n a l aand n d pprismatic r i s m a t i c crystal c r y s t a l outlines outlines aare r e ppresent r e s e n t .••• . . TTourmaline, o u r m a l i n e , sericite, s e r i c i t e , ccarbonate, a r b o n a t e , carbon, carbon, e p i d o t e , apatite, a p a t i t e , aand n d zzircon ircon w e r e aall l l rrecognized e c o g n i z e d in in epidote, were tthis h i s vvariety a r i e t y oof f jjasperoid a s p e r o i d aas s w e l l aas s iin n tthe h e anhedral anhedral well vvariety. ariety. T h e s e eeuhedral u h e d r a l qquartz u a r t z ggrains r a i n s average average These pprobably r o b a b l y 00015 . 1 5 tto o 00.2 .2 m i l l i m e t e r Iin n ddiameter, i a m e t e r , although although millimeter llocally o c a l l y tthe h e aavprage v e r a g e grain grain m a y bbe e aabout b o u t 00.5 . 5 tto o 0.7 0.7 may m i l l i m e t e r . ((1932, 1 9 3 2 , pp.. 98) 98) millimeter. 1 Gilluly where G i l l u l y ((1932, 1 9 3 2 , pp.. 999) 9 ) ddescribed e s c r i b e d pplaces laces w here ttwo w o ttypes y p e s bblend l e n d ttogether o g e t h e r aand n d rreports e p o r t s tthe he bbetween e t w e e n tthe h e ttwo w o aas s bbeing eing w avy. wavy. the the boundary boundary T h e aauthor u t h o r hhas a s ffound ound The llocation o c a t i o n iin n tthe he G eyser-Marion m i n e aarea rea w h e r e tthis his Geyser-Marlon mine where is is one one 33 33 clearly c l e a r l y shown s h o w n (Fig. ( F i g . 12). 12). Figure F i g u r e 13 1 3 iis s a photomicrograph photomicrograph of o f tthe h e rock r o c k type t y p e rrepres~nted e p r e s e n t e d by b y BM-l B M - 1 on o n Figure F i g u r e 12 12 which which iis s similar s i m i l a r to t o Gilluly's G i l l u l y s anhedral a n h e d r a l variety v a r i e t y of of 1 and a n d could c o u l d be b e called c a l l e d a siliceous s i l i c e o u s sinter. sinter. jasperoid jasperoid Some S o m e of o f the the q u a r t z ggrain~ r a i n s are a r e llarger a r g e r tthan h a n the t h e type t y p e reported r e p o r t e d a~nd n d some some quartz s h o w a ttendency e n d e n c y tto o euhedral e u h e d r a l form. form. show F i g u r e 14 1 4 iis s aa Figure p h o t o m i c r o g r a p h of o f the t h e rock r o c k type t y p e rrepresented e p r e s e n t e d by b y BM-2 on on photomicrograph F i g u r e 12 12 w h i c h iis s similar s i m i l a r to t o Gilluly's G i l l u l y ' s described described Figure which . "typical " t y p i c a l jjasperoid.asperoid." The T h e -typical " t y p i c a l jjasperoida s p e r o i d " is i s the the d o m i n a n t vv8riety a r i e t y of o f jjasperoid a s p e r o i d ppresent. resent. dominant T h e quartz q u a r t z grains grains The iin n thin t h i n section s e c t i o n hhave a v e wavy w a v y extinction e x t i n c t i o n showing s h o w i n g that t h a t they they hhave a v e bbeen e e n subjected s u b j e c t e d to to a s t r e s s field. field. stress G illuly Gilluly (1932, (1932, p . 100) 1 0 0 ) believes b e l i e v e s tthat h a t the t h e bbrecciated r e c c i a t e d character c h a r a c t e r of o f the the p. jjasperoid a s p e r o i d iis s due d u e to t o contraction c o n t r a c t i o n of o f the t h e colloidal-silica colloidal-silica gel w h i c h rreplaced e p l a c e d the t h e original o r i g i n a l llimestone imestone w h e n it it gel which when crystallized. crystallized. T h e stress s t r e s s of o f contraction c o n t r a c t i o n of o f tthe h e silica silica The gel m a s s could c o u l d hhave a v e caused c a u s e d the t h e deformation d e f o r m a t i o n of o f the the gel mass c r y s t a l l o g r a p h i c elements. elements. crystallographic C91cite C e l c i t e is i s present p r e s e n t in i n both b o t h types t y p e s of o f Jjasperoid a s p e r o i d but but more tthe h e 3nhedral a n h e d r a l vvariety a r i e t y contains contains m o r e calcite c a l c i t e in i n the the Geys~r-Marion G e y s e r - M a r i o n mine m i n e area a r e a than t h a n the t h e -typical "typical ttype. ype. jasperoid" jasperoid" The may T h e calcite c a l c i t e in i n the t h e anhedral a n h e d r a l variety variety m a y be be uunreplaced n r e p l a c e d limestone l i m e s t o n e as a s in i n the t h e euhedral e u h e d r a l vv~riety. ariety. may cc~lcite alcite m a y be b e hhypogene y p o g e n e as a s Gilluly G i l l u l y (1932, (1932, but b u t not n o t all. all. Some Some p. p . 99) 9 9 ) believes, believes, The T h e "typical " t y p i c a l jjasperoid" a s p e r o i d " is i s bplieved b e l i e v e d to to represent r e p r e s e n t a greater g r e a t e r amount a m o u n t of o f silicification s i l i c i f i c a t i o n than t h a n the the 334 4 Anhedral with FFigure i g u r e 112. 2. A n h e d r a l vvariety a r i e t y ((BM B M-- 1i) ) i1n n ccont~ct ontact w ith "-typical t y p i c a l vvariety· a r i e t y * ((BM B M-- 2) 2 ) vvariety a r i e t y oof f jasperold jasperoid i1n n tthe he G e y s e r - M a r i o n are~ a r e a ., Geyser-Marion oother t h e r ttype y p e aand n d tthus h u s rrepresents e p r e s e n t s aa ffurther u r t h e r sstage tage ccryst r y s t a~ ll the the of of development. development, G i l l u l y (1 ( 1 932. 9 3 2 , pp.. 999) 9 ) rrefers e f e r s tto o tthe h e cc aa rrbon b o n ffound ound G111uly tthe he jjasperolds a s p e r o i d s a~s s a a hhypogene ypogene m ineral. mineral. in 1n T h i ss 1s i s probably probably Thi o p e n tto o question q u e s t i o n since s i n c e tthe h e llimestone i m e s t o n e tthe h e qquartz u a r t z replaced replaced open pprobably r o b a b l y ccontained o n t a i n e d ccarbonaceous arbonaceous m a t e r i a l as a s ddoes o e s some some matprial tthe h e uunreplaced n r e p l a c e d 11mestone l i m e s t o n e . iln n .. tthe he of of sequence. sequence. T h e dlstrlbutlon d i s t r i b u t i o n oof f jjasperold a s p e r o i d from from L ion H i l l , whlch which The Llon H1H, i s south s o u t h of o f Ophir. O p h i r , tto o M e r c u r 1s i s of o f intere i n t e r e sst t becaus b e c a u s ee it it 1s Mereur m i g h t lead l e a d tto o some s o m e understanding u n d e r s t a n d i n g of o f the the might o f tthe h e a rres. ea. of iigneous gneous h i ss tt ory ory hi A l ttho h o uugh g h Gl11uly G i l l u l y has h a s stated s t a t e d that t h a t there t h e r e 1s is Al n o direct d i r e c t relat r e l a t iIo o nn between b e t w e e n the t h e jjas a s pperolds e r o i d s and a n d tthe h e intr i n t r usives usives no i n the t h e a rre e aa between b e t w e e n Llon Lion H i l l and a n d Mercur M e r c u r (1 ( 1 932 9 3 2 ,. p. p . 98) 9 8 ) ,. ln Hl11 35 Figure Photomicrograph F i g u r e 11). 3. P h o t o m i c r o g r a p h of o f tthe h e anhedral a n h e d r a l variety v a r i e t y of of crossed-nicols. 47X jjasperoid a s p e r o i d ((BM-i) B M - 1 ) .. crossed-nicols. 47X Figure 14. Photomicrograph of -typical jasperoid(BM-2). crossed-nlcols. 47X 36 36 Gold G o l d Ledge Ledge Metqmorphism M e t a m o r p h i s m of o f tthe h e gold g o l d ledge l e d g e varies v a r i e s according according tto o the t h e ppart a r t of o f tthe h e sedimentary s e d i m e n t a r y sequence s e q u e n c e mineralized mineralized and a n d closeness c l o s e n e s s tto o tthe h e Sacramento S a c r a m e n t o breccia b r e c c i a pipe. pipe. The T h e main main type t y p e of o f aadditive d d i t i v e metamorphism m e t a m o r p h i s m is i s silicification s i l i c i f i c a t i o n although although locally, l o c a l l y , along a l o n g with w i t h the t h e silica, s i l i c a , sericite, s e r i c i t e , illite, i l l i t e , qnd and c a l c i t e hhave a v e bbeen e e n deposited. deposited. calcite I l l i t e is i s abundant a b u n d a n t in i n the the Illite aaltered l t e r e d clay c l a y and a n d carbon c a r b o n rich r i c h area a r e a near n e a r tthe h e Sacrgmento Sacramento bbrecc r e c c iia a pipe. pipe. Metamorphism M e t a m o r p h i s m of o f the t h e Long L o n g Trail T r a i l Shale S h a l e in i n tthe h e Mercur Mercur area a r e a is i s llargely a r g e l y a silicification s i l i c i f i c a t i o n pprocess. rocess. The T h e quartz quartz gr8ins g r a i n s of o f tthe h e silicified s i l i c i f i e d rocks r o c k s are a r e anhedral, a n h e d r a l , resembling resembling the t h e aanhedr~l n h e d r a l vvariety a r i e t y of o f Jjasperoid, a s p e r o i d , yet y e t the t h e rock r o c k is is different d i f f e r e n t from f r o m the t h e ppreviously r e v i o u s l y discussed d i s c u s s e d ttype, y p e , which w h i c h is is similar s i m i l a r to t o a siliceous s i l i c e o u s sinter, s i n t e r , and a n d contains c o n t a i n s illite. illite. The The quartz q u a r t z present p r e s e n t is i s pprobably r o b a b l y recrystallized r e c r y s t a l l i z e d quartz q u a r t z from from tthe h e shale s h a l e and a n d siltstone s i l t s t o n e sequence; s e q u e n c e ; addition a d d i t i o n of o f quartz q u a r t z by by hhydrothermal y d r o t h e r m a l solutions s o l u t i o n s is i s vvery e r y pprobable. robable. T h e rock r o c k has h a s the the The a p p e a r a n c e of o f a siltstone s i l t s t o n e except e x c e p t tthat h a t it i t lacks l a c k s bedding. bedding. appearance T h e ppyrite y r i t e and a n d arsenopyrite a r s e n o p y r i t e ppresent r e s e n t are a r e invisible i n v i s i b l e to t o the the The e y e and a n d impart i m p a r t a degree d e g r e e of o f :false f a l s e bedding b e d d i n g to t o tthe h e rock r o c k in in eye tthin h i n section. section. A l t e r a t i o n of o f the t h e Long L o n g Trail T r a i l Shale, S h a l e , in i n the t h e Mercur Mercur Alteration H ill m i n e area a r e a is i s similar s i m i l a r to t o that t h a t in i n the t h e Brickyard B r i c k y a r d mine mine Hill mine area. area. C e r t a i n layers, l a y e r s , which w h i c h were w e r e probably p r o b a b l y limestone l i m e s t o n e layers layer Certain bbefore e f o r e silicification, s i l i c i f i c a t i o n , are a r e hhighly i g h l y silicified s i l i c i f i e d and a n d represent represent 37 37 a jasperoid. jasperoid. Some S o m e of o f the t h e bbeds e d s bbelow e l o w the t h e Long L o n g Trail T r a i l Shale Shale sequence Geyser-Marion mine s e q u e n c e in i n tthe he G eyser-Marion m i n e show s h o w grain g r a i n size size gradations g r a d a t i o n s and a n d bedding b e d d i n g strongly s t r o n g l y reminiscent r e m i n i s c e n t of o f aa siltstone s i l t s t o n e in i n thin t h i n section. section. These T h e s e beds b e d s are a r e only o n l y slightly slightly aaltered l t e r e d aalthough l t h o u g h they t h e y are a r e adjacent a d j a c e n t to t o hhighly i g h l y silicified silicified units. units. The T h e beds b e d s bbelow e l o w the t h e Long L o n g Trail T r a i l Shale S h a l e in i n tthe h e Mercur Mercur Hill H i l l mine m i n e area a r e a are a r e silicified s i l i c i f i e d and a n d in i n places p l a c e s are a r e sericiticized. sericiticized. What W h a t is i s most m o s t nnoticeable o t i c e a b l e aabout b o u t the t h e ore o r e sequence s e q u e n c e here h e r e is is tthe h e interlayering i n t e r l a y e r i n g of o f altered. a l t e r e d , slightly s l i g h t l y altered, a l t e r e d , and and uunaltered n a l t e r e d bbeds e d s iin n tthe h e ore o r e sequence. sequence. Remnant R e m n a n t bedding b e d d i n g is is visible v i s i b l e in i n the t h e altered a l t e r e d beds b e d s which w h i c h is i s one o n e characteristic characteristic tthat h a t is i s lacking l a c k i n g in i n the t h e silver s i l v e r lecig.e l e d g e or o r tthe h e "typical "typical jjasperoid." asperoid." T h e hhighly i g h l y altered a l t e r e d beds b e d s aare r e believed b e l i e v e d to to The rrepresent e p r e s e n t beds b e d s that t h a t once o n c e had h a d higher h i g h e r ppermeability e r m e a b i l i t y than than t h e other o t h e r beds b e d s and a n d thus t h u s could c o u l d serve s e r v e as a s channelways channelways the ffor o r solutions. solutions. S o m e of o f the t h e ffossils o s s i l s in i n the t h e altered a l t e r e d gold gold Some sequence which sequence w h i c h has h a s been b e e n silicified s i l i c i f i e d and a n d sericitized s e r i c i t i z e d appear appear to t o have h a v e bbeen e e n unaltered u n a l t e r e d during d u r i n g the t h e alteration a l t e r a t i o n processes processes and a n d ccont~in o n t a i n unreplaced u n r e p l a c e d calcite. calcite. IIn n one o n e of o f tthe h e quarry q u a r r y areas a r e a s in i n the t h e Mercur M e r c u r Hill H i l l mine mine one o n e side s i d e of o f a fault f a u l t in i n the t h e area a r e a is i s highly h i g h l y silicified s i l i c i f i e d to to jjasperoid a s p e r o i d whereas w h e r e a s the t h e other, o t h e r , sside i d e has h a s been b e e n less l e s s silicified silicified a n d hhas a s veinlets v e i n l e t s of o f ssericit(~ e r i c i t e pparallel a r a l l e l to t o remnant r e m n a n t bedding bedding and planes. planes. V e i n l e t s of o f calcite c a l c i t e cross-cut c r o s s - c u t quartz q u a r t z and a n d sericite sericite Veinlets i n t e r g r o w t h s in i n thin t h i n section section w i t h the t h e calcite c a l c i t e probably probably intergrowths with 38 38 bbeing e i n g hydrothermal h y d r o t h e r m a l in i n origin. origin. Several S e v e r a l generations g e n e r a t i o n s of of pyrite p y r i t e are a r e evident e v i d e n t with w i t h the t h e later l a t e r pyrite p y r i t e more m o r e qnhedrql anhedral in i n fform o r m (Fig. ( P i g . 15). 15). The T h e differing d i f f e r i n g alteration a l t e r a t i o n types t y p e s on on either e i t h e r side s i d e of o f tthe h e fault f a u l t are a r e believed b e l i e v e d to t o be b e due d u e tto o fault fault relations r e l a t i o n s and a n d to t o tthe h e effect e f f e c t of o f hhydrothermal y d r o t h e r m a l solutions solutions on o n differing d i f f e r i n g rock r o c k ttypes y p e s aand n d differing d i f f e r i n g sedimentary s e d i m e n t a r y sequences sequences which w h i c h had h a d bbeds e d s of o f higher h i g h e r permeability. permeability. Some S o m e fluorite f l u o r i t e was w a s found f o u n d in i n a comparatively c o m p a r a t i v e l y unaltered unaltered sequence s e q u e n c e at a t the t h e top t o p of o f Mercur M e r c u r Hill. Hill. The T h e sedimentary s e d i m e n t a r y sequence s e q u e n c e nnear e a r the t h e Sacramento S a c r a m e n t o breccia breccia pipe p i p e is i s bbelieved e l i e v e d to t o rrepresent e p r e s e n t either e i t h e r the t h e Long L o n g Trail Trail Sh~le S h a l e sequence s e q u e n c e or o r bbeds e d s below b e l o w it, i t . and a n d is i s characterized characterized locally l o c a l l y bby y beds b e d s hhaving a v i n g large l a r g e amounts a m o u n t s of o f illite. illite. iis s ppresent r e s e n t in i n vvarying a r y i n g amounts. amounts. Pyrite Pyrite The T h e area a r e a around a r o u n d the t h e breccia breccia p i p e is i s of o f interest i n t e r e s t bbecause e c a u s e of o f the t h e different different pipe alteration a l t e r a t i o n types t y p e s in i n which w h i c h carbon c a r b o n is i s present. present. One O n e sample sample assayed a s s a y e d for f o r carbon c a r b o n near n e a r number n u m b e r 3J on o n Figure Figure 6 6 had h a d 4.2% 4,2$ carbon c a r b o n present. present. Hydrocarbons H y d r o c a r b o n s are a r e clearly c l e a r l y visible v i s i b l e in in thin t h i n section s e c t i o n from f r o m rrock o c k samples s a m p l e s that t h a t show s h o w carbon c a r b o n associated associated w i t h clay clay m i n e r a l s that t h a t pprobably r o b a b l y formed f o r m e d in i n small s m a l l solution solution with minerals channelways c h a n n e l w a y s bbetween e t w e e n fractures. fractures. In I n the t h e area a r e a of o f number number 3 on o n Figure Figure 6 6 the t h e alteration a l t e r a t i o n vvaries a r i e s from f r o m a siliceous siliceous sinter s i n t e r with w i t h interstitial i n t e r s t i t i a l carbon c a r b o n to t o aan n illite-quartz illite-quartz rrock o c k with w i t h c~rbon. carbon. I t is i s questionable q u e s t i o n a b l e if i f any a n y of o f the the It c a r b o n - r i c h are~ a r e a is i s altered a l t e r e d intrusive, i n t r u s i v e , but b u t the t h e nearness nearness carbon-rich o f the t h e intrusive i n t r u s i v e tto o tthe h e carbon-rich c a r b o n - r i c h area a r e a is i s suggestive. suggestive. of 39 39 F i g u r e 15. 15P h o t o m i c r o g r a p h of o f altered a l t e r e d ggold o l d oore r e sequence sequence Figure Photomicrograph ffrom r o m tthe he M ercur H ill m i n e sshowing howing a a ccalcite a l c i t e velnlet veinlet Mercur Hill mine w i t h ppyrite y r i t e i1n n tthe h e ccenter enter w hich w a s ddeformed e f o r m e d by by with which was tthe h e llater a t e r ggrowth r o w t h oof f a a ppyrite y r i t e crystal. crystal, ttransm1tted r a n s m i t t e d l11ght. ight, 47X 47X cca, a , ccalcite; a l c i t e ; ppy, y , ppyrite; y r i t e ; qqtz tz + e r , qquartz u a r t z and and + sser, sserlctte e r i c i t e lIntergrowth; n t e r g r o w t h ; jj,, jjaroslte a r o s i t e stain stain S m a l l nnodules o d u l e s tthat hat m i g h t bbe e m o r e ssiliceous i l i c e o u s tthan han Small might more the the ssurrounding u r r o u n d i n g rrock o c k coan a n bbe e ffound o u n d i1n n tthe h e ccarbon-rich a r b o n - r i c h aarea r e a and and ccontain o n t a i n tthin h i n ffilms i l m s oof f ppyrite y r i t e aalong long fractures. fractures. Wavy x t i n c t i o n oof f tthe h e qquartz u a r t z ggrains r a i n s aand n d tthe he Wavy eextinction large large aamount m o u n t oof f sslickensided l i c k e n s i d e d ffragments r a g m e n t s i1n n tthe h e ccarbon-rich arbon-rich m i g h t rrepresent e p r e s e n t tthe h e sshock hock m e t a m o r p h i c eeffects f f e c t s tto o might metamorphic zone zone the the ssurrounding u r r o u n d i n g rrocks ocks w h e n tthe h e SSacramento a c r a m e n t o bbreccia r e c c i a ppipe i p e was was when fformed. ormed. SSome o m e oof f tthe h e ffragments r a g m e n t s i1n n tthe h e ccarbon-rich a r b o n - r i c h zone zone rresemble e s e m b l e pphyll h y l l ii tte e iin n hhand a n d sspecimen p e c i m e n bbecause e c a u s e oof f tthe he thoroughly thoroughly sslicke l i c k e nns s i ided d e d nna a tture u r e oof f tthe h e rrock o c k aand n d tthe h e hhigh i g h ccontent ontent cclay lay m inerals minerals of of present. present. No o t i c e a b l e hhydrothermal y d r o t h e r m a l aalteration lteration w a s eevident vident No nnoticeable was in in tthe h e l11mestone i m e s t o n e bbeds e d s aabove b o v e tthe h e ggold o l d lledge e d g e oon n tthe h e hh111 i l l beh1nd behind 40 40 the t h e Golden G o l d e n Gate G a t e mill m i l l site. site. Alter~tion A l t e r a t i o n associated a s s o c i a t e d with with with w i t h the t h e gold g o l d ore o r e sequence s e q u e n c e seems s e e m s to t o be b e restricted r e s t r i c t e d to to tthe h e more m o r e permeable p e r m e a b l e uunits n i t s and a n d does d o e s nnot o t vertically vertically ttranscend r a n s c e n d bbedding e d d i n g nnoticeably. oticeably. This T h i s would w o u l d seem s e e m to t o indicate indicate tthat h a t if i f one o n e were w e r e to t o look l o o k for f o r other o t h e r alteration a l t e r a t i o n associated associated with w i t h gold g o l d mineralization, m i n e r a l i z a t i o n , one o n e must m u s t find f i n d an a n actual actual altered a l t e r e d outcrop. outcrop. Weathering Weathering WeJ3.thering W e a t h e r i n g of o f the t h e silver s i l v e r ledge l e d g e or o r more m o r e characteristically characteristically of o f tthe h e Mtypical " t y p i c a l jjasperoid" a s p e r o i d " is i s ttypified y p i f i e d bby y alteration alteration of minerals o f sulfide sulfide m i n e r a l s to t o sulfates, s u l f a t e s , carbonates, c a r b o n a t e s , or o r oxides. oxides, Stibnite S t i b n i t e tthat h a t was w a s once o n c e ppresent r e s e n t alters a l t e r s to t o stibiconite stibiconite and a n d sulfur. sulfur. malachite. malachite. Copper-bearing C o p p e r - b e a r i n g sulfides s u l f i d e s alter a l t e r tto o azurite a z u r i t e and and Azurite A z u r i t e and a n d malachite m a l a c h i t e can c a n be b e found f o u n d on o n the the old o l d dumps d u m p s to t o the t h e west w e s t of o f the t h e old o l d Carrie C a r r i e Steele S t e e l e mine. mine. Some S o m e azurite a z u r i t e aand n d malachite m a l a c h i t e was w a s found f o u n d near n e a r the t h e old o l d Silver Silver C l o u d mine. mine. Cloud JJarosite, a r o s i t e , malachite, m a l a c h i t e , and a n d a blue-green b l u e - g r e e n alunite alunite are a r e found f o u n d in i n the t h e quarry q u a r r y aareas r e a s of o f the t h e old o l d Sparrowhawk S p a r r o w h a w k mine. mine. Weathering W e a t h e r i n g of o f the t h e gold g o l d ledge l e d g e is i s ttypified y p i f i e d by b y the the alteration a l t e r a t i o n of o f sulfide s u l f i d e minerals m i n e r a l s to t o sulfates s u l f a t e s or o r oxides. oxides. Gypsum many G y p s u m is i s found f o u n d in in m a n y of o f the t h e oxidized o x i d i z e d areas. areas. In I n the the protected p r o t e c t e d areas a r e a s uunderground n d e r g r o u n d halotrichite h a l o t r i c h i t e is i s locally locally abundant a b u n d a n t and a n d is i s uusually s u a l l y found f o u n d in i n the t h e oxidized o x i d i z e d zones. zones. IIt t takes t a k e s the t h e form f o r m of o f stalactites, s t a l a c t i t e s , hhelictites,needles, e l i c t i t e s , n e e d l e s , or or fibrous m asses. fibrous masses. P y r i t e alters a l t e r s to t o jjarosite a r o s i t e and a n d goethite; goethite; Pyrite 41 mainly jjarosite arosite m a i n l y gives g i v e s the t h e aaltered l t e r e d sequence s e q u e n c e iits t s yellow yellow color. color. Pisanite-melanterite P i s a n i t e - m e l a n t e r i t e (solid ( s o l i d solution s o l u t i o n series) series) i s ppresent r e s e n t in i n several s e v e r a l localities l o c a l i t i e s at a t Mercur M e r c u r aand n d iis s the the is main mineral main m i n e r a l in i n which w h i c h copper c o p p e r is i s found f o u n d hhere. ere. Peculiqrly. Peculiarly, iit t is i s found f o u n d predominantly p r e d o m i n a n t l y in i n tthe h e relatively r e l a t i v e l y unoxidized unoxidized pportions o r t i o n s oof f the t h e ore o r e sequence s e q u e n c e suggesting s u g g e s t i n g that t h a t tthe h e degree degree o f oxidation o x i d a t i o n of o f tthe h e ore o r e hhad a d some s o m e iinfluence n f l u e n c e aas s tto o llocation o c a t i o n of of of formation. formation. T h e ppisanite-melanterite i s a n i t e - m e l a n t e r i t e usually u s u a l l y iis s found found The t o occur o c c u r as a s fracture f r a c t u r e fillings fillings w h i c h might m i g h t hhave a v e resulted resulted to which e i t h e r from f r o m the t h e mineral's m i n e r a l ' s force f o r c e of o f crystallization c r y s t a l l i z a t i o n or or either t e c t o n i c activity. activity. tectonic A yellow y e l l o w variety v a r i e t y of o f scorodite s c o r o d i t e was was A f o u n d in i n the t h e Geyser-Marion Geyser-Marion m i n e area a r e a and a n d was w a s found f o u n d to to found mine hhave a v e resulted r e s u l t e d from f r o m the t h e direct d i r e c t oxidation o x i d a t i o n of o f oorpiment r p i m e n t with with t h e addition a d d i t i o n of o f iron. iron. the The weathering T he w e a t h e r i n g oof f the t h e Long L o n g Trail T r a i l Shale S h a l e iin n the the Brickyard mine Brickyard m i n e iis s of o f interest i n t e r e s t because b e c a u s e of o f the t h e lens-shaped lens-shaped nature n a t u r e of o f the t h e uunoxidized n o x i d i z e d pportions. ortions. Close C l o s e tto o tthe h e surface surface t h e oxidized o x i d i z e d pportions, o r t i o n s , in in m a n y instances, i n s t a n c e s , surround surround the many t h e uunoxidized n o x i d i z e d portions. portions. the A depth, Att depth, t h e unoxidized unoxidized the p o r t i o n s fform o r m columns c o l u m n s surrounded s u r r o u n d e d by b y oxidized o x i d i z e d matprial. material. portions F i g u r e 16 1 6 shows s h o w s the t h e lens-shaped l e n s - s h a p e d nature n a t u r e of o f tthe h e unoxidized unoxidized Figure p o r t i o n in i n a stope s t o p e of o f the the B r i c k y a r d mine. mine. portion Brickyard C a r b o n assays assays Carbon s h o w that t h a t both b o t h the t h e oxidized o x i d i z e d and a n d uunoxidized n o x i d i z e d portions portions show hhere e r e contain c o n t a i n lless e s s than t h a n 0.1% 0.1% carbon c a r b o n so s o the t h e bblack l a c k color color o f the t h e unoxidized unoxidized m a t e r i a l is i s probably p r o b a b l y due d u e tto o tthe h e presence presence of material o f finely f i n e l y disseminated d i s s e m i n a t e d pyrite p y r i t e and a n d arsenopyrite. arsenopyrite. of 442 2 S e m i - q u a n t i t a t i v e eemission m i s s i o n spectrographic s p e c t r o g r a p h s analyses analyses Semi-quantitative oof f tthe h e ooXidized x i d i z e d and a n d uunoxldlzed n o x i d i z e d pportions o r t i o n s sshown h o w n 1n in Figure Figure 1 6 are a r e ppresented r e s e n t e d 1n i n Table T a b l e J. 3. 16 F i g u r e 16. 16. P h o t o showing s h o w i n g rrelationships e l a t i o n s h i p s of o f weathered weathered Figure Photo ( m o t t l e d yyellow. ellow, w h i t e , aand n d brown) b r o w n ) tto o unweathered unweathered (mottled white. ((black) b l a c k ) strata s t r a t a 1n i n aa sstope t o p e oof f tthe he B r i c k y a r d mine. mine. Brickyard ALTERATION HILL ALTERATION OF OP THE EAGLE H I L L INTRUSIVE INTRUSIVE The T h e chief c h i e f varieties v a r i e t i e s of o f alteration a l t e r a t i o n of o f the t h e intrusive intrusive iinclude, n c l u d e , kkaolinization, aolinization, sericitization, s e r i c i t i z a t i o n , and a n d silicification. silicification, Kaolinite K a o l i n i t e is i s ppresent r e s e n t in i n small s m a l l amounts a m o u n t s throughout throughout the t h e intrusive. intrusive. The T h e aamount m o u n t of o f kaolinite k a o l i n i t e in i n tthe h e intrusive intrusive iincreases n c r e a s e s markedly m a r k e d l y around a r o u n d the t h e Sacramento S a c r a m e n t o breccia breccia where w h e r e the t h e intrusive I n t r u s i v e has h a s bbeen e e n highly h i g h l y altered. altered. pipe pipe The T h e rhyolite rhyolite dike d i k e at a t tthe h e mouth m o u t h of o f Mercur M e r c u r Ganyon G a n y o n has h a s also a l s o bbeen e e n highly highly altered a l t e r e d and a n d kaolinized. kaolinized. The T h e occurrence o c c u r r e n c e of of kaolinite k a o l i n i t e presumably p r e s u m a b l y resulted r e s u l t e d from f r o m early e a r l y high h i g h acid a c i d conditions conditions oof f the t h e hhydrothermal y d r o t h e r m a l solutions. solutions, Kaolinite K a o l i n i t e has h a s not n o t been been recognized r e c o g n i z e d ppreviously r e v i o u s l y in i n the t h e intrusive. intrusive. Sericite S e r i c i t e is i s very v e r y widespread w i d e s p r e a d in i n the t h e groundmass g r o u n d m a s s of of the t h e intrusive i n t r u s i v e as a s well w e l l as a s in i n tthe h e altered a l t e r e d sedimentary sedimentary sequence. sequence. It I t is i s definitely d e f i n i t e l y aa late l a t e mineral m i n e r a l and a n d was was pprobably r o b a b l y fformed o r m e d uunder n d e r less l e s s acid a c i d conditions c o n d i t i o n s than than the the kkaolinite. aolinite. C a l c i t e is i s ppresent r e s e n t in i n the t h e intrusive i n t r u s i v e and a n d is i s probably probably Calcite tthe h e result r e s u l t of o f hydrothermal h y d r o t h e r m a l activity a c t i v i t y although a l t h o u g h some some weathering. bbe e tthe h e rresult e s u l t of of w eathering. could could Some S o m e of o f the t h e calcite c a l c i t e replaces replaces pplagioclase, l a g i o c l a s e . bbut u t most m o s t occurs o c c u r s randomly r a n d o m l y distributed distributed in in t h e altered a l t e r e d groundmass. groundmass. the Silicification S i l i c i f i c a t i o n is i s the t h e most m o s t widespread w i d e s p r e a d of o f the the alteration a l t e r a t i o n ttypes y p e s and a n d hhas a s completely c o m p l e t e l y aaffected f f e c t e d the t h e intrusive. intrusive. Q u a r t z has h a s bbeen e e n aadded d d e d to t o the t h e ffine-grained i n e - g r a i n e d groundrnass groundmass Quartz 44 44 in i n all a l l thin t h i n sections s e c t i o n s studied. studied. rrims i m s of o f coarse-grained coarse-grained Some S o m e pphenocrysts h e n o c r y s t s have have quartz. quartz. The T h e are3 a r e a 3round a r o u n d tthe h e Sacramento S a c r a m e n t o breccia b r e c c i a pipe p i p e is is highly h i g h l y altered a l t e r e d (Fig. ( F i g . 4 and a n d 17). 1?). Most M o s t of o f the t h e quartz quartz aand n d biotite b i o t i t e pphenocrysts h e n o c r y s t s have h a v e been b e e n hydrothermally hydrothermally removed removed and a n d all a l l tthe h e pplagioclase l a g i o c l a s e and a n d sanidine s a n i d i n e pphenocrysts h e n o c r y s t s seem seem to t o hhave a v e been b e e n hhydrothermally y d r o t h e r m a l l y rremoved. emoved. ~he The addition a d d i t i o n of of qquartz u a r t z containing c o n t a i n i n g numerous n u m e r o u s inclusions i n c l u s i o n s is i s pronounced pronounced t h i s part p a r t of o f the t h e intrusive. intrusive. this in in T h e intrusive i n t r u s i v e has h a s been b e e n very very The s i l i c i f i e d hhere e r e as a s hhas a s the t h e sedimentary s e d i m e n t a r y sequence s e q u e n c e next next silicified t o tthe h e ppipe. ipe. to T h e altered a l t e r e d intrusive i n t r u s i v e in i n tthis h i s area, a r e a , as as The ppreviously r e v i o u s l y mentioned, m e n t i o n e d , contains c o n t a i n s kaolinite k a o l i n i t e and and sericite sericite a n d a 1ittle l i t t l e calcite. calcite. and T w e n t y - t h r e e samples s a m p l e s from f r o m tthe h e iintrusive n t r u s i v e and a n d the the Twenty-three altered with a l t e r e d sedimentary s e d i m e n t a r y sequence s e q u e n c e iin n contact contact w i t h it i t were were analyzed Zn, Ag, a n a l y z e d for f o r Mn, Mn, Z n, A g , and a n d Cu C u bby y atomic a t o m i c absorption absorption spectrophotometry s p e c t r o p h o t o m e t r y (Fig. ( F i g . 17 1 7 and a n d Table T a b l e 1). 1), The T h e purpose purpose was w a s tto o see s e e if i f any a n y anomalous a n o m a l o u s values v a l u e s occurred o c c u r r e d in i n the the hhighly i g h l y altered a l t e r e d portions p o r t i o n s compared c o m p a r e d tto o the t h e less l e s s altered altered areas. areas. T h e mean m e a n pplus l u s two t w o standard s t a n d a r d ddeviation e v i a t i o n values values w e r e taken t a k e n to to The were be which b e anomalous a n o m a l o u s values values w h i c h for f o r tthe h e elements e l e m e n t s tested t e s t e d would would b e : Mn (1)5.) ( 1 3 5 * 3 pppm), p m ) , Zn Z n ()4.6 ( 3 ^ . 6 pppm), p m ) , Ag (7.4 ( 7 . ^ ppm), p p m ) , and a n d Cu Cu be: ( 1 3 . 1 pppm). pm). (1).1 anomalous ~nomalous S a m p l e s 102, 1 0 2 , 109, 1 0 9 , 1)0, 1 3 0 , 1)2, 1 3 2 , and a n d 1)) 1 3 3 showed showed Samples v a l u e s bbut u t only o n l y 102 1 0 2 and a n d 109 1 0 9 are a r e in I n the t h e highly highly values altered a l t e r e d area. area. No trend t r e n d is i s rreadily e a d i l y apparent a p p a r e n t between between the the h i g h l y altered a l t e r e d and a n d the t h e slightly s l i g h t l y altered a l t e r e d samples s a m p l e s but b u t atomic atomic highly ^45 5 L~.~&nd ieg&nd ~6b (::rc,t FL.lt' Lim'::'Gton1J M Great chgb E.lC~:~ Flue ;!1ll Llm?ctons rhyullt. ch Eagle Mill rhyolite ~::~~ t~r("d Altered intrusive ~. ~11!clC~~d co~ntry rQc~ *• Silicified country rocK ! ~~:fie *• Sample lcc~tl~h location » fault 1l".t:'US1VC Hob 1'-----,, 134 • y >. t 305 *«3« _ «4Ci \ \ JUBi • Mob \ > , IlJ ' " 133* ,,....-.~~ \, 131* ,,' -"" .. _--- } N JO5 fcV ,, , ' ' ,, .... , , Mgb K gb ... ... \ , , ' '- ~ " ... , - " .~.I th eh I" ~ I th th ,----" " " 1 Seale Seal* 1000 h.t 0o 1000 f«*t ~=C-::::J £ 3 - Hgb \ \ 11gb \ ',"\ , "" "" ... , Mgb '... ..... , -- b s o r p t i o n Values Values Table Absorption T a b l e 1.--Atomlc i .—Atomic A Mn Highly Altered H i g h l y Altered 6ppru 6 ppm 102 445 5 109 77.5 77.5 305 305 40lJ 404 4405 05 406 406 407 702 9 5 6 69 69 2 Slightly S l i g h t l y Altered Altered 100 1}0 130 101 131 162.5 132 162.5 50 133 1Jl} 134 )5 35 40 301 40 52.5 302 52.5 65 30) 65 303 86.5 306 86.5 90 307 65 309 309 401 401 35 62.5 402 62.5 65 403 65 403 IWq 103 40§ Zn 10ppm 10 ppm 37.5 37.5 17.5 17.5 16 9 7 9 Ag 8ppro 8 ppm 44 1.5 1.5 1~ k 1.5 1.5 22 .• 5.1&; 1.5 1.5 0 4.5 4.5 46 46 2.5 2.5 9 66 2.5 2.5 10 4 7.5 7.5 7 5.) 5.3 14 0 )3 5 8 2.5 2,5 32.5 32.5 L~ 4 8 2.5 2.5 1.5 1.5 2.5 2.5 4 4 2 5 2.5 2.5 4.5 4.5 4.5 4.5 5 1.5 1.5 •• '-': ,,--' tomic a p showing s h o w i n g aatomic Figure 17. G General m~p geology m e n e r a l geology s a m p l e locatloDA. locations. absorption p t i o n sample Semple Sample lC~ Cu 44ppm ppm 14 14 5 2.5 2.5 11 5 66 2~5 2.5 44 66 2.5 2.5 2.5 2.5 11 11 66 2., 2 o 44 2.5 2.5 2.5 2.5 11 2.5 2.5 2.5 2,5 2.5 2.5 0 )O} • J 46 46 absorption a b s o r p t i o n values v a l u e s for f o r other o t h e r samples s a m p l e s from f r o m the t h e altered altered sedimentary s e d i m e n t a r y sequence s e q u e n c e show s h o w higher h i g h e r values v a l u e s ffor o r Zn Z n than than in i n the t h e uunaltered n a l t e r e d sequence. sequence. Silicification S i l i c i f i c a t i o n of o f the t h e country c o u n t r y rock r o c k around a r o u n d the the intrusive i n t r u s i v e (Fig. ( P i g . 44) ) is i s apparently a p p a r e n t l y related r e l a t e d to t o fluids f l u i d s which which e m a n a t e d from f r o m tthe h e intrusive. intrusive. emanated T h e degree d e g r e e of o f alteration alteration The a r o u n d the t h e Sacramento S a c r a m e n t o breccia b r e c c i a ppipe i p e is i s quite q u i t e pronounced; pronounced; around tthe h e altered a l t e r e d sedimentary s e d i m e n t a r y sequence s e q u e n c e shows s h o w s intense intense silicification. silicification. T h e area a r e a of o f silicification s i l i c i f i c a t i o n around a r o u n d sample s a m p l e site s i t e #305 # 3 0 5 and and The t h e area a r e a tto o tthe h e south s o u t h aare r e pprobably r o b a b l y related r e l a t e d to t o the the the d e p o s i t i o n oof f quartz q u a r t z bby y hydrothermal h y d r o t h e r m a l ffluids l u i d s from f r o m the the deposition intrusive. intrusive. T h e s e ttwo w o silicified s i l i c i f i e d areas areas w e r e the t h e only o n l y areas areas These were w h e r e llarge a r g e ppyrite y r i t e crystals c r y s t a l s and a n d ppyritized yritlzed where found. found. ff~ssils ossils were were S a m p l e #305 # 3 0 5 was w a s found f o u n d to t o contain c o n t a i n 16 1 6 ppm gold gold Sample ( 0 . 4 6 oz oz A u/ton) w h i c h suggests s u g g e s t s that t h a t gold g o l d deposition d e p o s i t i o n was was (0.46 Au/ton) which r e l a t e d to t o hhydrothermal y d r o t h e r m a l aactivity c t i v i t y that t h a t arose a r o s e as a s aa related c o n s e q u e n c e of o f igneous i g n e o u s activity. activity. consequence T h e silicified s i l i c i f i e d aarea r e a near near The s a m p l e site s i t e #309 # 3 0 9 is i s also a l s o eevidently v i d e n t l y rrelated e l a t e d to t o hydrothermal hydrothermal sample activity. activity. T h e silicification s i l i c i f i c a t i o n tto o the t h e SE S B of o f the t h e SE S B corner corner The of F i g u r e 4. 4 , nnear e a r the t h e intrusive, i n t r u s i v e , also a l s o is i s pprobably r o b a b l y related related of Figure tto o hhydrothermal y d r o t h e r m a l activity. activity. T h e s e occurrences o c c u r r e n c e s seem s e e m to to These i n d i c a t e that t h a t tthe h e contact c o n t a c t between b e t w e e n the t h e intrusive i n t r u s i v e and a n d the the indicate c o u n t r y rrock o c k was w a s favorable f a v o r a b l e ffor o r the t h e ppassage a s s a g e of o f solutions solutions country w h i c h replaced r e p l a c e d ccalcite a l c i t e and a n d deposited d e p o s i t e d quartz q u a r t z in i n the the which rock. rock. country country T h e three t h r e e roof r o o f pendants p e n d a n t s not n o t removed r e m o v e d by b y erosion e r o s i o n from from The t h e roof r o o f of o f tthe h e intrusive i n t r u s i v e show s h o w no n o noticeable n o t i c e a b l e alteration. alteration. the 47 The weathering T h e cchemical hemical w e a t h e r i n g oof f tthe h e iintrusive n t r u s i v e iis s ssubtle. ubtle. v~ry very IIn n pparts a r t s oof f tthe h e iintrusive, ntrusive, w e a t h e r i n g hhas a s removed removed weathering m o r e oof f sspecific p e c i f i c llayers a y e r s rresulting e s u l t i n g iin n llayered a y e r e d rridges idges more ggive i v e tthe h e rrock o c k aa ffalse-flowage a l s e - f l o w a g e ccharacter. haracter, that that N e a r tthe h e Sacramento Sacramento Near bbreccia r e c c i a ppipe, i p e , ssmall m a l l hhematite e m a t i t e sspots p o t s iin n tthe h e iintrusive n t r u s i v e might might rrepresent e p r e s e n t tthe h e fformer o r m e r ppresence r e s e n c e oof f ffinely i n e l y disseminated disseminated ppyrite. yrite. S o m e oof f tthe h e bbiotite i o t i t e fflakes l a k e s aat t tthe h e surface s u r f a c e are are Some w eathered. weathered. The Eagle Hill T he E agle H i l l iintrusive n t r u s i v e sshows h o w s progressive progressive metamorphism Mercur m e t a m o r p h i s m iin n tthe he M e r c u r aarea. rea. The T h e ggroundmass r o u n d m a s s was was with pprobably r o b a b l y tthe h e ffirst i r s t tto o bbe e aaltered ltered w i t h ssanidine a n i d i n e being being altered with a l t e r e d tto o kkaolinite a o l i n i t e and a n d then t h e n to t o sericite sericite w i t h decreasing decreasing acid a c i d conditions. conditions. Plagioclase P l a g i o c l a s e pphenocrysts h e n o c r y s t s are a r e rare r a r e in i n the the intrusive were i n t r u s i v e at a t Mercur M e r c u r and a n d apparently apparently w e r e hydrothermally hydrothermally rremoved. emoved. T h e amount a m o u n t of o f bbiotite i o t i t e present p r e s e n t appears a p p e a r s tto o bbe e aa The g o o d iindicator n d i c a t o r of o f hhydrothermal y d r o t h e r m a l alteration. alteration. good W h e r e biotite biotite Where i s absent a b s e n t or o r scarce s c a r c e hhydrothermal y d r o t h e r m a l alteration a l t e r a t i o n hhas a s bbeen e e n most most is intense. intense. T h e iron i r o n from f r o m the t h e biotite b i o t i t e is i s believed b e l i e v e d tto o have have The g o n e toward t o w a r d the t h e formation f o r m a t i o n of o f pyrite. pyrite. gone S a n i d i n e phenocrysts phenocrysts Sanidine a l s o are a r e less l e s s common c o m m o n where w h e r e hydrothermal h y d r o t h e r m a l alteration a l t e r a t i o n was was also m o r e intense. intense. more Q u a r t z phenocrysts p h e n o c r y s t s also a l s o seem s e e m to t o be b e indicative indicative Quartz o f the t h e intensity i n t e n s i t y of o f alteration a l t e r a t i o n although a l t h o u g h to t o a lesser l e s s e r degree degree of t h a n the t h e lack l a c k of o f biotite, b i o t i t e , plagioclase, p l a g i o c l a s e , and a n d sanidine sanidine than phenocrysts. phenocrysts. Q u a r t z phenocrysts p h e n o c r y s t s are a r e not n o t common c o m m o n in in Quartz t h e intrusive i n t r u s i v e near n e a r the t h e Sacramento S a c r a m e n t o breccia b r e c c i a pipe. pipe. the THE GOLD DEPOSITS DEPOSITS The T h e gold g o l d deposits d e p o s i t s are a r e replacement r e p l a c e m e n t deposits d e p o s i t s that that are a r e largely l a r g e l y stratigraphically s t r a t i g r a p h i c a l l y controlled. controlled. They T h e y are are characterized mineralogically characterized m i n e r a l o g i c a l l y by b y the t h e presence p r e s e n c e oof f orp1ment, orplment, realgar r e a l g a r (Fig. ( F i g , 18), 1 8 ) , arsenopyrite, a r s e n o p y r l t e , finely f i n e l y disseminated disseminated pyrite, p y r i t e , and a n d locally l o c a l l y cinnabar. cinnabar. Galena. G a l e n a , cinnabar, c i n n a b a r , sphalerite, sphalerite, sulvanite. s u l v a n i t e , and a n d chalcopyrite c h a l c o p y r i t e have h a v e been b e e n reported r e p o r t e d although although they were they w e r e not n o t observed o b s e r v e d bby y the t h e author. author. Spurr S p u r r (1894-95, (189^-95, p. p . 4)0) 4 3 0 ) reported r e p o r t e d the t h e presence p r e s e n c e of o f rrealgar e a l g a r as a s bbeing e i n g aa favorable f a v o r a b l e sign s i g n of o f gold g o l d mineralization, m i n e r a l i z a t i o n , but b u t nnot o t always. always. All A l l pprevious r e v i o u s investigators i n v e s t i g a t o r s report r e p o r t the t h e gold g o l d as a s nnot o t being being visible was v i s i b l e in i n ppolished o l i s h e d section s e c t i o n although a l t h o u g h it it w a s rreported e p o r t e d as as bbe1ng e i n g vvisible i s i b l e bby y use u s e of o f the t h e reflecting r e f l e c t i n g microscope m i c r o s c o p e once once t h e ore o r e had h a d been b e e n roasted. roasted. the T h e author, a u t h o r , through t h r o u g h study s t u d y of of The p o l i s h e d sections s e c t i o n s from f r o m the t h e ore o r e sequence. sequence, w a s unable unable polished was t o detect d e t e c t any a n y visible v i s i b l e gold. gold. to The T h e presence p r e s e n c e of o f orpiment o r p l m e n t and a n d realgar r e a l g a r iis s usually usually attributed a t t r i b u t e d to t o llow o w temperature t e m p e r a t u r e hydrothermal h y d r o t h e r m a l environments, environments, such s u c h as a s hhot o t springs. springs. The Mercur T h e gold g o l d deposits d e p o s i t s at at M e r c u r probably probably are a r e of o f the t h e epithermal e p i t h e r m a l type t y p e and a n d were w e r e pprobably r o b a b l y emplaced emplaced at a t shallow s h a l l o w depths d e p t h s in i n a typical t y p i c a l hot h o t spring s p r i n g environment. environment. Nichols Bureau N i c h o l s and a n d Peterson P e t e r s o n (1970) ( 1 9 7 0 ) of o f the t h e U.S. U.S. B u r e a u of of Mines M i n e s made m a d e a study s t u d y of o f the t h e mill m i l l tailings t a i l i n g s at a t Mercur M e r c u r aimed aimed at a t devising d e v i s i n g a profitable p r o f i t a b l e method m e t h o d for f o r extracting e x t r a c t i n g the the r e m a i n i n g gold g o l d from f r o m the t h e tailings. tailings. remaining T h e y state s t a t e tthat h a t the1r their They " q u a l i t a t i v e analytical a n a l y t i c a l methods m e t h o d s showed s h o w e d that t h a t ggold o l d is is -qualitative 49 F i g u r e 18. 18. P h o t o shol<ling s h o w i n g oorpiment r p l m e n t (yellow) ( y e l l o w ) and a n d re r eaa lgar lgar Figure Photo ((red) r e d ) 1n i n tthe h e uunoxidized n o x i d i z e d zzone o n e of o f tthe h e Brickyard Brickyard m i n e .. The w h i t e pportions o r t i o n s aare r e tthe h e ssulfate ulfate mine The white m e l a n t e r i t e --pisanlte pisanite w h i c h iis s present. present. melanterite which aassociated ssociated w i t h all all m i n e r a lls s w i t h aa hhigher igher with minera with iin n tthe h e oorga r g a nnic i c aand nd m agnetic m inerals* magnetic minerals· 11970 9 7 0 ,. pp.. c o n c e n t r a t ion ion concentrat ( N i c h o l s aand n d Peterson. Peterson, (Nichols 6). 6). G o l d sseemingly e e m i n g l y hhas a s bbeen een m i n e d ffrom r o m tthe he Gold mined altered altered ssedimentary e d i m e n t a r y bbeds e d s iin n ccontact ontact w i t h oor r ffrom r o m tthe he with zzones o n e s aat t M ercur. Mercur. breccia breccia T h e ttwo w o ssIlIcified i l i c i f i e d bbreccia r e c c i a ppipes ipes ~he aas s cc hhannelways a n n e l w a y s ffo o rr hhydrothermal y d r o t h e r m a l ssolutions, o l u t i o n s , bbut u t ddo o aappear p p e a r tto o hhave a v e bbeen een m i n e d ffor o r ggo o lld. d. mined T h e zzones ones The a c ted ted ac not not around around tt hhe e bbreccia r e c c i a ppipes i p e s hhave a v e bbeen een m i n e d ffor o r ggold, old, w hich mined which suggests suggests tthat h a t ggo o lld d ddeposition e p o s i t i o n ppreceded r e c e d e d ppipe i p e fformation o r m a t i o n oor r tthat hat zzones o n e s aaround r o u n d tthe h e ppipes ipes w ere m o r e ffavorable a v o r a b l e ffor or were more g o ld ld go ddeposition e p o s i t i o n tthan h a n tthe h e bbreccia r e c c i a ppipes i p e s tthemselves. hemselves. The The ff aqu u lIt t bbreccia r e c c i a zzones o n e s aappe p p e a~r r tto o hhave a v e fformed o r m e d llater a t e r tthan han the the the the 50 50 h y d r o t h e r m a l alteration, a l t e r a t i o n , but b u t gold g o l d enrichment e n r i c h m e n t could c o u l d h~ve have hydrothermal ooccurred c c u r r e d from f r o m the t h e solution s o l u t i o n and a n d rremoval e m o v a l of o f calcite. calcite. Cinnabar C i n n a b a r was w a s mined m i n e d commercially c o m m e r c i a l l y for f o r mercury mercury only o n l y at a t the t h e Sacramento S a c r a m e n t o gold g o l d mine m i n e in i n the t h e Mercur M e r c u r camp. camp. Mercury w a s rreported e p o r t e d to t o occur o c c u r in i n trace t r a c e amounts a m o u n t s as as Mercury was cinnabar w i t h the t h e gold g o l d deposits d e p o s i t s in i n the t h e other other m i n e s of of cinnabar with mines t h e ccamp. amp. the T h e commercial c o m m e r c i a l concentrations c o n c e n t r a t i o n s of o f mercury mercury The a t the t h e Sacramento S a c r a m e n t o mine m i n e could c o u l d be b e ccaused a u s e d bby y tthe h e ssame a m e processes processes at t h a t formed f o r m e d the t h e Sacramento S a c r a m e n t o bbreccia r e c c i a pipe. pipe. that U n s a f e conitions conitions Unsafe f o r entry e n t r y to t o the t h e old o l d mine mine w o r k i n g s did d i d nnot o t allow allow for workings e x a m i n a t i o n of o f the t h e ore o r e sequence s e q u e n c e uunderground n d e r g r o u n d at a t the the examination S a c r a m e n t o mine. mine. Sacramento E x a m i n a t i o n of o f tthe h e quarry q u a r r y area a r e a did d i d not not Examination r e v e a l the t h e presence p r e s e n c e of o f any a n y cinnabar. cinnabar. reveal General G e n e r a l paragenetic p a r a g e n e t i c relations r e l a t i o n s for f o r the t h e ggold old de~osits deposits can c a n be b e given g i v e n from f r o m general g e n e r a l field, f i e l d , polished p o l i s h e d section, s e c t i o n , or or t h i n section s e c t i o n observations. observations. thin T h e replacement r e p l a c e m e n t of o f calcite calcite The i n the t h e limestone l i m e s t o n e beds b e d s by b y quartz q u a r t z pprobably r o b a b l y occurred o c c u r r e d first. first. in L o c a l l y sericite s e r i c i t e and a n d illite i l l i t e accompany a c c o m p a n y the t h e quartz. quartz. Locally Pyrite Pyrite and a n d arsenopyrite a r s e n o p y r i t e deposition d e p o s i t i o n followed f o l l o w e d with w i t h anhedral a n h e d r a l pyrite pyrite f o r m i n g bbefore e f o r e the t h e euhedral e u h e d r a l pyrite. pyrite. forming A n h e d r a l pyrite pyrite Anhedral a n d arsenopyrite a r s e n o p y r i t e viewed v i e w e d in i n thin t h i n section s e c t i o n occur o c c u r between between and t h e individual i n d i v i d u a l quartz q u a r t z grains g r a i n s in i n rrocks o c k s from f r o m tthe h e Brickyard Brickyard the mine. m ine. Euhedral was E u h e d r a l pyrite, p y r i t e , in i n ppolished o l i s h e d section, section, w a s observed observed t o have h a v e formed f o r m e d around a r o u n d the t h e quartz q u a r t z grains. grains. to O r p i m e n t and and Orpiment r e a l g a r are a r e apparently a p p a r e n t l y late l a t e minerals m i n e r a l s since s i n c e tthey h e y occur occur realgar a s fracture f r a c t u r e and a n d vug v u g fillings. fillings. as S o m e of o f tthe h e best best Some 51 crystalline c r y s t a l l i n e realgar r e a l g a r was w a s found f o u n d in i n limestone l i m e s t o n e vugs vugs s u r r o u n d e d by b y calcite c a l c i t e crystals. crystals. surrounded T h e time t i m e at a t which which The g o l d deposition d e p o s i t i o n occurred o c c u r r e d is i s unknown u n k n o w n because b e c a u s e gold g o l d could cou gold n o t be b e seen. seen. not S i n c e galena, g a l e n a , sphalerite, s p h a l e r i t e , and a n d cinnabar cinnabar Since w e r e not n o t observed o b s e r v e d their t h e i r paragenetic p a r a g e n e t i c relations r e l a t i o n s also also were a r e unknown. unknown. are ELEMENTAL ANALYSES OF ELEMENTAL OP ROCK SAMPLES SAMPLES Qualitative Q u a l i t a t i v e emission e m i s s i o n spectrographic s p e c t r o g r a p h s analyses a n a l y s e s of of rock r o c k samples s a m p l e s from f r o m the t h e gold g o l d ledge l e d g e ssequence e q u e n c e are a r e ggiven i v e n in in T a b l e 2. 2. Table T h e similarity s i m i l a r i t y of o f elemental e l e m e n t a l composition c o m p o s i t i o n between between The rrocks o c k s from f r o m the t h e slightly s l i g h t l y altered a l t e r e d Long L o n g Trail T r a i l Shale Shale tthe h e altered a l t e r e d Long L o n g Trail T r a i l Shale Shale rock rock ((~~101) G-101) (C-103), (C-l03). ( 6 0 2 ) , and a n d the t h e carbon-rich carbon-rich (602), i s of o f interest I n t e r e s t beoause b e c a u s e the t h e intensity I n t e n s i t y of of is a l t e r a t i o n apparently a p p a r e n t l y does d o e s not n o t affect a f f e c t the t h e eelements l e m e n t s present. present. alteration T h e unaltered u n a l t e r e d Lower L o w e r Great Great The B l u e Limestone Limestone ~ue s a m p l e (501) (501) sample w a s collected c o l l e c t e d from f r o m the t h e southern s o u t h e r n part p a r t of o f the t h e Geyser-Marion Geyser-Marion was mine. mine. T h e altered a l t e r e d Lower L o w e r Great G r e a t Blue B l u e Limestone L i m e s t o n e (305) (305) The sample sample w a s collected c o l l e c t e d from from a a silicified-pyritized silicified-pyritized was n e x t to t o the t h e intrusive. intrusive. next zone zone T h e differences d i f f e r e n c e s in i n elemental elemental The c o m p o s i t i o n are a r e obvious o b v i o u s between b e t w e e n these t h e s e two t w o rrock o c k samples samples composition w i t h the t h e aaltered l t e r e d rock r o c k sample s a m p l e showing s h o w i n g tthe h e ppresence r e s e n c e of of with gold. gold. T h e presence p r e s e n c e of o f As, A s , B, B , Au, A u . Pb, P b , Hg, H g , K. K , Si. Si, A g , TI, Tl, The Ag. and Z n characterize c h a r a c t e r i z e the t h e altered a l t e r e d samples s a m p l e s and a n d aare r e believed believed and Zn t o rrepresent e p r e s e n t elements e l e m e n t s deposited d e p o s i t e d from f r o m hhydrothermal y d r o t h e r m a l solutions. solutions. to S e m i - q u a n t l t a t l v e emission e m i s s i o n spectrographic s p e c t r o g r a p h l c analyses analyses Semi-quantitative for f o r three t h r e e rock r o c k samples s a m p l e s are a r e given g i v e n in i n Table T a b l e 3. 3. The T he values values given g i v e n should s h o u l d nnot o t bbe e taken t a k e n to t o represent r e p r e s e n t exact e x a c t vvalues a l u e s but but o n l y to t o rrepresent e p r e s e n t an a n element's e l e m e n t ' s presence. presence. only T he The detection detection l i m i t for f o r tellurium t e l l u r i u m is i s 00.01% . 0 1 $ which w h i c h indicates i n d i c a t e s tellurium tellurium limit i s nnot o t present p r e s e n t in i n sufficient s u f f i c i e n t concentrations c o n c e n t r a t i o n s iin n these these is s a m p l e s to t o bbe e detected. detected. samples O t h e r unpublished u n p u b l i s h e d analyses analyses Other 53 T a b l e 22.--Qualitative . — Q u a l i t a t i v e Emission E m i s s i o n Spectrographic Spectrographs Table Analyses Rock A n a l y s e s of of R o c k Samples S a m p l e s From Prom Mercur. M e r c u r , Utah Utah Element E lement 602 602 C-103 C'-103 C-101 C-10l Ag Ag Al Al As As Au Au X X X X X X X X X X X Tr Tr B X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Tr Tr X X X X Ca Ca Cr Cr Fe Fe Hg K Mg Mn Mn Na P b Pb Si Si Ti Ti Tl TI Zn Zn 501 501 305 305 X X X Tr Tr Tr Tr X X X X X r a i l Shale Shale a l t e r e d Long Long T C-103--slightly Trail c - 1 0 3 - - s l i g h t l y altered ine o c k , Sacramento Sacramento m C-10l--carbon-rich mine C - 1 0 1 - - c a r b o n - r i c h rrock, ine S h a l e , Brickyard Brickyard m 6 0 2 — - g o l d ore, L o n g Trail T r a i l Shale, 602----gold mine o r e , Long B l u e Limestone Limestone L o w e r Great G r e a t Blue 501----unaltered 5 0 1 — - u n a l t e r e d nower L o w e r Great Great B l u e Limestone Limestone 305----altered Blue 3 0 5 — - a l t e r e d Lower X e l e m e n t present present X---element T r — t r a c e of o f element e l e m e n t present present Tr--trace X X X X X X X X X X X X X X Tr Tr X X X X X X X 5* Table T a b l e J.--Semi-quantitative 3 - — S e m i - q u a n t i t a t i v e Emission E m i s s i o n Spectrographic Spectrographic A n a l y s i s oof f Rock R o c k Samples S a m p l e s From F r o m Mercur. M e r c u r , Utah Utah Analysis Weathered Unweathered gold Unweathered gold ore ore Weathered gold gold ore ore Br1ckyard mine m1ne Br1ckyard m1ne Brickyard mine Brickyard .0001* .0005% .000U .0005* Ag Ag ca 4.0 ca AI Al ca 4.0 ca 5.0 5.0 .1) .12 A8 As .12 .13 N.D •. N.D. Au Au N.O. N.D.. .008 .008 B B .008 .008 .02 .03 BIt Ba .02 .03 .0003 .0003 Be Be .0003 .0003 N.D •. N.D. B1 Bi N.D. N.D.. Ca .003 .05 Ca .003 .05 N.D. N.D. Cb Cb N.D. N.D. N.D. N.D. Cd Cd N.D. N.D. N.D. N.D. Ce Ce N.D. N.D. <..001 < .001 Co Co <.001 <.001 .004 .005 Cr Cr .005 .004 .20 .BO Cu Cu .80 .20 ca ca 4.0 Fe Pe ca 4.0 4.0 ca.001 4.0 <.<.001 < Ga Ga < .001 .001 N.D. N.D •. Ge Ge N.D.. N.D. N.D. N.D. at Hf N.D. N.D. N.D •. N.D. Bg Hg N.D.. N.D. <.001 < In In < .001 .001 <.001 .01 .01 La La .01 .01 fig .15 .15 Mg .15 .15 .001 .003 Mn .001 .003 <.001 (.001 Mo <.001 <.001 .07 .03 !fa Na .03 .07 .0004 .0007 .1 Ni .000? .0004 pP .04 .06 .04 .06 .0004 .0004 Pb Pb .0004 .0004 N.D. N.D. I'd Pd N.D. N.D. N.D •. N.D. Pt Pt N.D. N.D.. .001 .001 8b Sb .001 .001 ca ca 81 Si ca 20.0 20.0 ca 20.0 20.0 N.D. .0003 8n N.D. .0003 Sn N.D •. N.D. Ta Ta N.D. N.D.. N.D. N.D. Te Te N.D. N.D. N.D. N.D. Th Th N.D. N.D. '1',. .15 .15 Ti .15 .15 .004 .003 V V .003 .004 N.D. N.D V N.D..•. N.D* w .002 .002 I· Y .002 .002 ca ca ZD Zn ca .1 .1 ca .1 .1 .01) .008 Zr Zr .008 .013 not detected N.D. approx1mately ca ca approximately less thlln less than < < Research Center Woods, Kennecott Analyzed Analyzed by R. R. Woods, Kennecott Research Center Element Element "" "0 Carbon-r1ch rock Carbon-rich rock Sacramento m1ne Sacramento mine .0006* .0006% ca ca 3.0 3.0 .02 .02 N.D •. N.D.. .01 .01 .01 .01 .0002 .0002 N.D. N.D. .20 .20 N.D. N.D. N.D. N.D. N.D. N.D. <..001 <.001 .006 .006 .15 .15 ~a ca 3.0 3.0 < .001 .001 N.D. N.D. N.D. N.D. N.D. N.D. .(1 .001 .001 <.<.01 .01 .15 .15 .0005 .0005 (.001 <.001 .30 .30 .0005 .0005 .03 .03 .0005 .0005 N.D. N.D. N.D. N.D. .001 .001 ca ca 20.0 20.0 .0003 .0003 N.D. N.D. N.D. N.D. N.D. N.D. .10 .10 .006 .006 N.D. N.D. .003 .003 <.01 <.01 .005 .005 55 55 show s h o w tellurium t e l l u r i u m iis s ppresent r e s e n t as a s ppreviously r e v i o u s l y ppublished u b l i s h e d analyses analyse hhave a v e shown. shown. T h e bboron o r o n ppresent r e s e n t is i s believed b e l i e v e d to t o be b e hheld e l d in in The tthe h e crystal c r y s t a l structure s t r u c t u r e oof f the t h e cclay l a y minerals. minerals. T h e source source The f o r tthe h e bboron oron w a s pprobably r o b a b l y tthe h e hhydrothermal y d r o t h e r m a l solutions solutions for was tthat h a t at a t one o n e ttime i m e ppervaded e r v a d e d the t h e sequence. sequence. T h e high high The ppercentage e r c e n t a g e of o f copper c o p p e r is i s of o f iintereRt n t e r e s t since s i n c e nno o previously previously ppublished u b l i s h e d analyses analyses copper. copper. iindicate n d i c a t e any a n y more m o r e than t h a n a ttrace r a c e of of The T h e high h i g h copper c o p p e r analyses a n a l y s e s comes c o m e s from f r o m a portion portion o f the t h e sequence s e q u e n c e that t h a t does d o e s contain c o n t a i n melanterite-pisanite melanterite-pisanite of bbut u t the the s a m p l e selected s e l e c t e d did d i d not n o t have h a v e any a n y of o f tthe h e sulfate sulfate sample m i n e r a l visible. visible. mineral A t o m i c absorption a b s o r p t i o n aanalysis n a l y s i s vvalues a l u e s for for M n, Z n , Ag, Ag, Atomic Mn, Zn, and C u for f o r other o t h e r selected s e l e c t e d samples s a m p l e s showed s h o w e d a hhigh i g h amount amount and eu o f zinc z i n c to t o bbe e present p r e s e n t in i n the t h e altered a l t e r e d sequence s e q u e n c e compared compared of tto o tthe h e unaltered u n a l t e r e d sequence. sequence. T h e uunaltered n a l t e r e d limestone limestone The (501) which ( 5 0 1 ) showed s h o w e d a hhigh i g h amount a m o u n t of o f silver s i l v e r (10 ( 1 0 ppm) ppm) w h i c h the the qqu~litative u a l i t a t i v e emission e m i s s i o n spectrographic s p e c t r o g r a p h i c analysis a n a l y s i s failed failed tto o show. show. IMPLICATIONS I M P L I C A T I O N S OF CARBON AND ORGANIC COMPOUNDS COMPOUNDS The T h e association a s s o c i a t i o n of o f carbon c a r b o n with w i t h the t h e gold g o l d deposits deposits o f Mercur M e r c u r has h a s been b e e n known k n o w n for f o r many m a n y years. years. of M a n y investigators investigators Many h a v e studied s t u d i e d the t h e ability a b i l i t y of o f carbon. c a r b o n and a n d organic o r g a n i c acids acids have t o precipitate p r e c i p i t a t e gold g o l d from f r o m solution. solution. to O n g and a n d Swanson Swanson Ong ( I 9 6 9 ) have h a v e found f o u n d that t h a t colloidal c o l l o i d a l gold g o l d can c a n be b e precipitated precipitated (1969) f r o m gold g o l d chloride c h l o r i d e solutions s o l u t i o n s by b y certain c e r t a i n organic o r g a n i c acids. acids. from T h e y state s t a t e that. t h a t , -in * i n acidic a c i d i c solutions, s o l u t i o n s , for f o r example e x a m p l e near near They o r e deposits d e p o s i t s where w h e r e the t h e pH is i s often o f t e n less l e s s than t h a n 3, 3 , gold g o l d can can ore b e transported t r a n s p o r t e d as a s gold g o l d chloride c h l o r i d e ions. ions. be H o w e v e r , organic organic However, a c i d s are a r e not n o t soluble s o l u b l e in i n this t h i s acid a c i d environment e n v i r o n m e n t and a n d are are acids tthus h u s incapable i n c a p a b l e of o f ttransporting r a n s p o r t i n g ggold. old. I f organic o r g a n i c acids acids If h a v e bbeen e e n pprecipitated r e c i p i t a t e d nnear e a r an a n ore o r e ddeposit e p o s i t the t h e gold g o l d itself itself have w i l l bbe e precipitated p r e c i p i t a t e d from f r o m solution s o l u t i o n as a s colloids c o l l o i d s of of will metallic metallic g o l d aand n d incorporated incorporated w i t h tthe h e organic o r g a n i c matterm a t t e r * (Ong (Ong gold with a n d Swanson. S w a n s o n , 1969. I969. P 421), and p.- 421). T h e y ggive i v e no n o criteria c r i t e r i a for for They sstating t a t i n g tthat h a t oorganic r g a n i c acids a c i d s aare r e nnot o t ssoluble o l u b l e iin n aan n e n v i r o n m e n t oof f less l e s s tthan h a n aa pH of o f 3» environment 3. ((1970, 1970, R a d t k e aand nd Radtke Scheiner Scheiner pp., 997), 7), w h o hhave a v e ddone one w o r k oon n tthe he C arlin who work Carlin ddeposit, eposit, hhave a v e cconducted o n d u c t e d oorganic r g a n i c extractions e x t r a c t i o n s oon n ggold o l d oore r e ssamples a m p l e s ffrom rom C arlin, N e v a d a , aand n d hhave ave Carlin. Nevada. tthem h e m tto o ccontain o n t a i n hhumic u m i c aacids. cids, ((If I f tthey hey m ean mean gold gold carbon-rich carbon-rich found found carboxylic carboxylic aacids c i d s tthe h e iinfrared n f r a r e d sspectra p e c t r a tthey h e y ppresent r e s e n t ddo o nnot ot tto o aa ccarboxylic a r b o x y l i c aacid c i d sspectra.) pectra.) acid acid F r o m tthe h e fflow low From correspond correspond diagram diagram ffor o r aa NaOH x t r a c t i o n ggiven i v e n bby y D e g e n s aand nd R euter NaOH eextraction Degens Reuter (1964, (1964. 5'1 5? p. would p - 385) 3 8 5 ) one w o u l d eexpect x p e c t tto o o n e eextr~ct x t r a c t hhumic u m i c aacids. cids. bbelieve e l i e v e most m o s t of o f the t h e gold g o l d occurs o c c u r s as a s an an They They organometallic organometallic complex Au (I) most c o m p l e x in i n the t h e Au ( I ) valence v a l e n c e state s t a t e and a n d thus thus m o s t of of the t h e gold g o l d is I s not n o t present p r e s e n t in i n a free f r e e state s t a t e iin n tthe h e rocks. rocks. Variations V a r i a t i o n s of o f the t h e organic o r g a n i c extraction extraction Degens ggiven i v e n bby y D e g e n s and a n d Reuter R e u t e r (1964) (1964) techniques techniques were w e r e used u s e d bby y tthe h e author author on Utah; o n samples s a m p l e s from f r o m Mercur, Mercur, U t a h ; Getchell G e t c h e l l Mine, M i n e , Nevada Nevada ( s a m p l e taken t a k e n from f r o m dump); d u m p ) ; and a n d the t h e Newmont Newmont m i n e , Carlin, Carlin, (sample mine, Nevada N evada (sample ( s a m p l e from f r o m the t h e east e a s t pit), p i t ) , to t o determine d e t e r m i n e if if hydrocarbons h y d r o c a r b o n s were w e r e present. present. Three T h r e e methods m e t h o d s of o f extraction, e x t r a c t i o n , which w h i c h will w i l l bbe e described described briefly b r i e f l y bbelow, e l o w , were w e r e used u s e d on o n crushed c r u s h e d carbon-rich c a r b o n - r i c h rock rock samples s a m p l e s with w i t h the t h e organic o r g a n i c extract e x t r a c t bbeing e i n g dissolved d i s s o l v e d in i n CCl C C l 4^ b e f o r e being b e i n g injected i n j e c t e d into i n t o Wilks W i l k s cells c e l l s for f o r uuse s e iin n aa before Beckman B e c k m a n IR"20 I R * 2 0 spectrophotometer. spectrophotometer. The T h e infrared i n f r a r e d spectra spectra o b t a i n e d were w e r e compared c o m p a r e d against a g a i n s t the t h e spectra s p e c t r a for f o r pure pure obtained C C l ^ to t o determine d e t e r m i n e which w h i c h organics o r g a n i c s were w e r e present. present. CCl4 Extraction Extraction t e c h n i q u e s involved i n v o l v e d using u s i n g aa mixture m i x t u r e of o f bbenezene, e n e z e n e , methanol. methanol, techniques a n d aacetone: c e t o n e ; 0.3 0,3 N a O H ; or o r 0.5 0.5 N NH/jAc solutions. solutions. and N N NaOH; N NH4Ac In I n the t h e benezene-methanol-acetone b e n e z e n e - m e t h a n o l - a c e t o n e method m e t h o d (70:15:15 (70:15:15 by b y volume), v o l u m e ) , the t h e B-M-A B - M - A mixture m i x t u r e was w a s found f o u n d to t o leave l e a v e an an infrared i n f r a r e d detectable d e t e c t a b l e residue r e s i d u e which w h i c h was w a s deleterious d e l e t e r i o u s to to interpretation Getchell i n t e r p r e t a t i o n of o f the t h e Mercur, M e r c u r , Carlin, C a r l i n , and and G e t c h e l l samples. samples. The N NaOH T h e organic o r g a n i c extraction e x t r a c t i o n technique t e c h n i q u e using u s i n g aa 00.3 .3 N solution more s o l u t i o n was w a s found f o u n d to t o be be m o r e effective e f f e c t i v e than t h a n tthe h e B-M-A B-M-A 58 58 method. method. I n this t h i s method m e t h o d NaOH w a s allowed a l l o w e d tto o precolate precolate In was t h r o u g h the t h e sample s a m p l e which which w a s on o n a fiberglass f i b e r g l a s s ffilter i l t e r paper paper through was with iin n a Buchner B u c h n e r funnel funnel w i t h the t h e solution s o l u t i o n being b e i n g aallowed l l o w e d to to collect c o l l e c t in i n a beaker. beaker. The was T h e leachant leachant w a s then t h e n pplaced l a c e d in in p l a s t i c bottle b o t t l e with w i t h CC1 C C l ^ and s h a k e n on o n a paint paint a plastic 4 a n d shaken f o r )0 3 0 minutes. minutes. for shaker sh~ker T h e CCI4. C C 1 ^ which w h i c h is i s heavier h e a v i e r tthan h a n the the The # NaOH, w a s drawn d r a w n off o f f and a n d partially p a r t i a l l y evaporated e v a p o r a t e d tto o concentrate concentrate NaOH, was any WqS a n y organics o r g a n i c s ppresent--the r e s e n t — t h e solution solution w a s then t h e n iinjected n j e c t e d into into W i l k s cell c e l l for f o r use u s e on o n the t h e infrared i n f r a r e d spectrophotometer. spectrophotometer. a Wilks E x t r a c t i o n using u s i n g a 0.5 0.5 N N NH4Ac NH^Ac solution s o l u t i o n oon n the the Extraction Mercur, was M e r c u r , Carlin, C a r l i n , and a n d Getchell G e t c h e l l samples s a m p l e s also also w a s ffound o u n d to to b e effective. effective. be T h e NH^Ac s o l u t i o n was w a s allowed a l l o w e d tto o percolate percolate The NH4Ac solution through t h r o u g h the t h e sample s a m p l e on o n a fiberglass f i b e r g l a s s filter f i l t e r ppaper a p e r iin n aa B u c h n e r funnel. funnel. BUchner T h e solution s o l u t i o n was w a s evaporated e v a p o r a t e d in i n a beaker beaker The b e l o w BOoc 8 0 ° C on o n a hotplate. hotplate. below CCI4 w a s then t h e n added a d d e d and and CC14 was s t i r r e d to t o dissolve d i s s o l v e any a n y organics. organics. stirred T h e CCl4 CCl^ w a s allowed allowed The was t o ppartially a r t i a l l y evaporate e v a p o r a t e to t o concentrate c o n c e n t r a t e any a n y oorganics r g a n i c s and and to t h e solution s o l u t i o n was w a s then t h e n injected i n j e c t e d into i n t o a Wilks W i l k s cell c e l l for f o r use use the o n the t h e infrared i n f r a r e d spectrophotometer. spectrophotometer. on A n ion i o n exchange exchange An c o l u m n of o f amberlite a m b e r l i t e MB-3 MB-3 w a s tried t r i e d before b e f o r e tthe h e above above column was d e s c r i b e d method m e t h o d to t o remove r e m o v e the t h e acetate a c e t a t e ion i o n aand n d gave g a v e the the described s a m e results. results. same T h e extractions e x t r a c t i o n s and a n d filling f i l l i n g of o f the t h e Wilks W i l k s cell cell The s h o u l d be b e performed p e r f o r m e d under u n d e r a fume f u m e hood h o o d with w i t h tthe h e Wilks Wilks should c e l l being b e i n g flushed flushed w i t h CC14 CCl/^ several s e v e r a l times t i m e s bbetween e t w e e n samples. samples. cell with The T h e infrared i n f r a r e d spectra s p e c t r a for f o r the t h e samples s a m p l e s are a r e presented presented --, 59 59 in i n Figure F i g u r e 19 1 9 9nd a n d 20. 20. The N NaOH T h e 0.3 0,3 N extraction extraction (Fig. ( F i g . 19) 1 9 ) was w a s found f o u n d tto o contain c o n t a i n organics o r g a n i c s of o f the t h e alkane alkane group w h i c h hhave a v e aa characteristic c h a r a c t e r i s t i c infrared i n f r a r e d absorption absorption group which -1 bband a n d aaround r o u n d 2900 2 9 0 0 cm c m " .• 1 T h e 00.5 .5 N NH^Ac N NH4Ac The extraction extraction ( F i g . 20) 2 0 ) was w a s found f o u n d to t o dissolve d i s s o l v e carboxylic c a r b o x y l i c acids a c i d s (carbonyl (carbonyl (Fig. g r o u p — n o t bbelieved e l i e v e d tto o bbe e acetic a c e t i c acid) acid) group--not w h i c h have h a v e aa which c h a r a c t e r i s t i c infrared i n f r a r e d absorption a b s o r p t i o n bband a n d aaround r o u n d 1700 1 7 0 0 cmc m ~1 * characteristic a n d some s o m e organics o r g a n i c s of o f tthe h e alkane a l k a n e group. group. and ( A l k a n e s are a r e one one (Alkanes o f tthe he m a i n hhydrocarbon y d r o c a r b o n constituents c o n s t i t u e n t s of o f petroleum.) petroleum.) of main O r g a n i c acids a c i d s aand n d methane m e t h a n e are a r e kknown n o w n pproducts r o d u c t s of o f bacterial bacterial Organic a c t i o n but b u t the t h e author a u t h o r iis s uuncertain ncertain w h e t h e r the t h e carboxylic carboxylic action whether a c i d s are a r e bbacterial a c t e r i a l pproducts. roducts. gcids T h e carboxylic c a r b o x y l i c acids acids The c o u l d aalso l s o bbe e organic o r g a n i c decay d e c a y products p r o d u c t s introduced i n t r o d u c e d by by could g r o u n d water. water. ground Some S o m e mobilization m o b i l i z a t i o n of o f carbon c a r b o n in i n a hydrothermal hydrothermal environment p.- 273) e n v i r o n m e n t hhas a s bbeen e e n suggested s u g g e s t e d by b y Joralemon J o r a l e m o n (1951. (1951. P 273) for Mine, Nevada, f o r tthe h e gold g o l d deposit d e p o s i t aat t Getchell Getchell M ine, N e v a d a , aand n d by by Hausen H a u s e n and a n d Kerr K e r r (1968, ( 1 9 6 8 , p. p , 930) 9 3 0 ) for f o r tthe h e gold gold at Nevada. a t Carlin, Carlin, N evada, deposit deposit The T h e author a u t h o r found f o u n d nnear e a r the t h e Sacramento Sacramento breccia b r e c c i a pipe p i p e aa small s m a l l veinlet v e i n l e t of o f interstitial i n t e r s t i t i a l carbon carbon aalong long w h i c h aa small s m a l l offset o f f s e t hhad a d occurred. occurred. which T h e small small The f r a c t u r e pprobably r o b a b l y served s e r v e d as a s aa conduit c o n d u i t for f o r an a n organic organic fracture r i c h solution s o l u t i o n with w i t h tthe h e carbon c a r b o n dispersing d i s p e r s i n g into i n t o the the rich s u r r o u n d i n g rock. rock. surrounding N e a r the t h e same s a m e location location Near carbon-rich carbon-rich m a t e r i a l abuts a b u t s aagainst g a i n s t a hhighly i g h l y altered a l t e r e d outcrop o u t c r o p of o f rock rock material w hich m i g h t bbe e altered a l t e r e d intrusive i n t r u s i v e and a n d whose whose which might physical physical 660 0 "I Wavelength in In Micron* Micron. Wavelength • ... , U '0 It II 20 ••• • ••• •S T T. I t• t to II II 1.4. ,1,. 10 4.1 —i 1 • i i • i 1 1—H r—i*"-!—i —i r I - CCI 10 40 1—r 4 Sacramento Mi Mine, Sacramento no, Mereu" Mercur, Utah Utah Brickyard Mine, Mine, Mercur, Mere ur, Utah Utah Brickyard long Trail Trail Shale, Shale, Ophir, Ophir, Utah Utah long Carlin, Carlin. Nevada Nevada r-----..,------.. . . Getchell Getchell Mine, Mine, Nevada Nevada .000 JOOO 1000 1000 •••• 1000 •• 00 1*00 1400 1400 Wavenumber Wavenumber CmCm"'l noo 1100 1000 .000 100 .00 Figure Infrared F i g u r e 19. 19. I n f r a r e d spectra s p e c t r a of o f 0.3 0 * 3 N NaOH organic organic extractions e x t r a c t i o n s from f r o m rock r o c k samples s a m p l e s associated a s s o c i a t e d with with gold g o l d deposits. deposits. *00 .00 .00 400 61 u l' 1.1 '.1 • ... , , .• e " '0 "11 ,.. '. 10 20 Sacramenta Mine, Mercur, Utah Brickyard Mine, Mereur, long Utah Troll Shale, Ophir, Utah Carlin, Nevada Getchell Mine, 3000 4000 Nevada 2000 1eoo 1600 Wavenumber 1400 1200 tooo eoo em-' Figure Infrared F i g u r e 20 20. I n f r a r e d spectra s p e c t r a of o f 0.5 0.5 N N NHaAc NHjhAc organic organic extractions from rock samples assoc1ated e x t r a c t i o n s f r o m r o c k s a m p l e s a s s o c i a t e d with with gold g o l d deposits. deposits. 0 600 400 ... 62 r e l a t i o n might m i g h t be b e due d u e to t o faulting. faulting. relation S o m e carbon carbon Some s t r e a m i n g into i n t o healed h e a l e d fractures f r a c t u r e s in i n the t h e altered a l t e r e d mass m a s s is is streaming apparent. apparent. T h e altered a l t e r e d mass m a s s consists c o n s i s t s of o f calcite, calcite, The k a o l i n i t e , quartz, q u a r t z , and a n d illite. illite. kaolinite, T h e carbon c a r b o n is i s not not The r e s t r i c t e d to t o one o n e rock r o c k type t y p e at a t the t h e Sacramento S a c r a m e n t o breccia breccia restricted p i p e , which w h i c h suggests s u g g e s t s either e i t h e r movement m o v e m e n t of o f carbon c a r b o n and/or and/or pipe, h y d r o c a r b o n s or o r varying v a r y i n g degrees d e g r e e s of o f alteration. alteration. hydrocarbons No e v i d e n c e for f o r solution s o l u t i o n thinning, t h i n n i n g , which w h i c h might m i g h t have h a v e caused caused evidence c a r b o n enrichment, e n r i c h m e n t , was w a s seen s e e n in i n the t h e Sacramento S a c r a m e n t o mine m i n e area. area, carbon b u t this t h i s does d o e s not n o t mean m e a n it i t did d i d not n o t happen. happen. but T h e presence p r e s e n c e of o f carbon c a r b o n is i s believed b e l i e v e d to t o be b e due d u e to to The t h e rreducing e d u c i n g action a c t i o n of o f ppast a s t hhydrothermal y d r o t h e r m a l solutions solutions the on might o n aany n y hhydrocarbons y d r o c a r b o n s that that m i g h t hhave a v e bbeen e e n ppresent r e s e n t in in t h e shales s h a l e s and a n d siltstones. siltstones. the T h e question q u e s t i o n of o f whether whether The h y d r o c a r b o n s and/or a n d / o r carbon c a r b o n are are m o b i l e is i s an a n unanswered unanswered hydrocarbons mobile q u e s t i o n , bbut u t field f i e l d evidence e v i d e n c e and a n d tthin h i n section s e c t i o n study study question, ssuggest u g g e s t tthat h a t tthere h e r e hhas a s bbeen e e n aan n aapparent pparent m o b i l i t y of of mobility ccarbon a r b o n aand nd hydrocarbons• hydrocarbons. SULFUR ISOTOPIC I S O T O P I C DATA SULFUR Twenty T w e n t y samples s a m p l e s of o f sulfur s u l f u r bbearing e a r i n g minerals m i n e r a l s were were collected mines c o l l e c t e d ffrom r o m vvarious arious m i n e s around a r o u n d tthe h e ghost g h o s t town t o w n of of M ercur, Mercur. U tah, Utah. f o r a sulfur s u l f u r isotopic i s o t o p i c study s t u d y (Fig. ( F i g . 21). 21). for Primary P r i m a r y bbarite a r i t e occurs o c c u r s in i n tthe h e silver s i l v e r ledge l e d g e from f r o m which which silver s i l v e r was w a s produced p r o d u c e d iin n tthe h e early e a r l y days d a y s of o f the t h e district. district. Secondary S e c o n d a r y sulfates s u l f a t e s occur o c c u r as a s jjarosite. a r o s i t e , alunite, a l u n l t e , melanteritemelanteriteppisanite, i s a n i t e , hhalotrichite, a l o t r l c h i t e , scorodite. s c o r o d l t e , and and gypsum. gypsum. Natroalunite was N atroalunite w a s found f o u n d iin n several s e v e r a l pplaces l a c e s outside outside Mercur West M e r c u r camp c a m p (Clay ( C l a y Canyon C a n y o n and and W e s t Mercur). Mercur). the the Primary Primary s u l f i d e s occur o c c u r as a s ppyrite. y r i t e , orpiment, o r p l m e n t , realgar. r e a l g a r , cinnabar. cinnabar, sulfides a r s e n o p y r i t e , stibnite, s t i b n i t e , chalcopyrite. c h a l c o p y r i t e , sulvanite, sulvanite, arsenopyrite. s p h a l e r i t e , and a n d galena. galena. sphalerite. S e c o n d a r y sulfide s u l f i d e occurs occurs Secondary s p a r i n g l y as a s elemental e l e m e n t a l sulfur. sulfur. sparingly c o m m o n in i n tthe h e district. district. common P r i m a r y sulfides s u l f i d e s are are Primary not not P y r i t e is i s tthe h e most m o s t common c o m m o n sulfide sulfide Pyrite f o u n d in i n the t h e old o l d quarry q u a r r y areas. areas. found Sulfur S u l f u r dioxide d i o x i d e was w a s prepared p r e p a r e d from f r o m sulfides s u l f i d e s and and sulfates methods s u l f a t e s bby y m e t h o d s outlined; o u t l i n e d , bby y M~L. M»L. Jensen J e n s e n at a t the the Laboratory University L a b o r a t o r y of o f Isotope I s o t o p e Geology, Geology, U n i v e r s i t y of o f Utah. Utah. The The 0 sulfides w e r e bburned u r n e d in i n a vvacuum a c u u m at a t 850 8 5 0 ° GC for f o r 15 1 5 minutes minutes sulfides were w i t h copper c o p p e r oxide o x i d e tto o pproduce r o d u c e S02. S0 • with T h e 502 SO2 and a n d CO C0 The 2 formed w e r e separated s e p a r a t e d in i n a series s e r i e s of o f cold c o l d ttraps. raps. The formed were The 2 2 S0 a n d CO G0 w e r e ffirst i r s t collected c o l l e c t e d in i n a liquid l i q u i d nitrogen nitrogen S02 and 2 were trap. T h e frozen f r o z e n 502 S0 a n d CO C0 e r e allowed a l l o w e d tto o sublimate sublimate trap. The and were 2 w 2 2 2 2 o n c e tthe h e liquid l i q u i d nnitrogen i t r o g e n ttrap rap w a s rremoved e m o v e d and a n d collected collected once was 64 64 in N-pentane i n a trap t r a p of of N - p e n t a n e frozen f r o z e n by b y liquid l i q u i d nitrogen. nitrogen. An intervening i n t e r v e n i n g ccold o l d trap t r a p oof f acetone a c e t o n e and a n d dry d r y ice i c e removed removed any water any w a t e r present. present. Allowing N-pentane A l l o w i n g tthe he N - p e n t a n e to t o melt, melt, gaseous The g a s e o u s CO C 0 2 is i s first f i r s t rreleased e l e a s e d leaving l e a v i n g the t h e S02' S0 . T h e S02 S0 is i s collected c o l l e c t e d in i n a gas g a s flask f l a s k ffor o r mass m a s s spectrometric spectrometric 2 2 2 analysis. analysis• The T h e sulfates s u l f a t e s are a r e prepared p r e p a r e d bby y rreacting e a c t i n g them t h e m with w i t h aa mixture HNO which m i x t u r e of o f HI, HI, H N O ^ , and HC1 pproducing roducing H H2SS w h i c h is is J a n d HCI bbubbled u b b l e d through t h r o u g h a cadmium c a d m i u m acetate a c e t a t e solution s o l u t i o n tto o produce produce 2 CdS. CdS. T h e CdS C d S is i s converted c o n v e r t e d to to A g S by b y adding a d d i n g AgNOJ AgNO^ The Ag2S 2 solution. solution. The T h e ddried r i e d Ag A g2SS is i s bburned u r n e d bby y tthe h e same s a m e procedure procedure 2 a s tthe h e sulfides s u l f i d e s tto o produce p r o d u c e S02. S0 • as 2 The samples were T h e S02 S0 samples w e r e analyzed a n a l y z e d on o n a mass m a s s spectrometer spectrometer 2 by b y Joseph J o s e p h Jensen J e n s e n with w i t h the t h e calculations c a l c u l a t i o n s bbeing e i n g made m a d e bby y the the author. author. Table Table 4 4 shows s h o w s tthe h e rresults e s u l t s of o f tthe h e analyses. analyses. Sulfur S u l f u r isotopic i s o t o p i c composition c o m p o s i t i o n of o f a sulfur-bearing sulfur-bearing mineral m i n e r a l is i s controlled c o n t r o l l e d by b y aa number n u m b e r of o f factors factors including, including, according Ohmoto a c c o r d i n g to to O h m o t o (1972, ( 1 9 7 2 , pp.. 55J) 5 5 3 ) -(1) " ( 1 ) tthe h e relative relative isotopic i s o t o p i c enrichment e n r i c h m e n t factors f a c t o r s of o f aqueous a q u e o u s sulfur s u l f u r species, species, (2) ( 2 ) tthe h e mole m o l e fractions f r a c t i o n s of o f aqueous a q u e o u s sulfur s u l f u r species, s p e c i e s , and and ()) ( 3 ) the t h e mean m e a n isotopic i s o t o p i c composition c o m p o s i t i o n of o f sulfur s u l f u r in i n the the solutions.solutions." Ohmoto O h m o t o (1972, ( 1 9 7 2 , pp.. 5556) 5 6 ) further f u r t h e r states s t a t e s that, that, -the " t h e mole m o l e fractions f r a c t i o n s of o f aaqueous q u e o u s sulfur s u l f u r species s p e c i e s relative relative tto o ttotal o t a l sulfur s u l f u r content c o n t e n t are a r e dependent d e p e n d e n t on o n the the equilibrium equilibrium c o n s t a n t s for f o r the t h e reactions, r e a c t i o n s , the t h e activity a c t i v i t y coefficients coefficients constants o f aqueous a q u e o u s species, s p e c i e s , the t h e fugacity f u g a c i t y of o f oxygen, o x y g e n , the t h e pH, pH, of .65 CONTOUR INTERVAL 40 FEET DATUM IS MEAN MEAN SEA SEA LEVEL DATU M IS Ll VEL Figure Map Mercur~ g u r e 21~ 21. M a p of o f ppart a r t of o f tthe he M e r c u r . Utah U t a h topographic topographic quadrangle q u a d r a n g l e showing s h o w i n g collection c o l l e c t i o n sites s i t e s aand n d sample sample nnumbers u m b e r s for f o r the t h e sulfur s u l f u r isotope i s o t o p e samples. samples. 66 TTable a b l e 44. . SSulfur u l f u r iisotope sotope SSample ample 11--orpiment - -orpiment data. data. 66 34 ^ S Area A r e a oof f ++4.83 4.83 Geyser-Marion G e y s e r - M a r i o n mine mine s Collection Collection 22--realgar - -realgar 77.13 .13 Mercur Hill M ercur H i l l mine mine 33--realgar --realgar 66.28 .28 Geyser-Marion G e y s e r - M a r i o n mine mine 44--orpiment - -orplment 44.63 .63 B r i c k y a r d mine mine Brickyard 55--orplment - -orplment 15.80 15*80 B r i c k y a r d mine mine Brickyard 66--realgar --realgar 88.90 .90 B r i c k y a r d mine mine Brickyard 77--realgar --realgar 66.57 .57 Brickyard B r i c k y a r d mine mine 8--barite 8- - b a r l t e 9--orpirnent 9- -orplment 15.26 15-26 G e y s e r - M a r i o n mine mine Geyser-Marion 99.51 .51 G e y s e r - M a r i o n mine mine Geyser-Marion 10--pyrite 10- -pyrite 11.55 11.55 Sacramento S a c r a m e n t o mine mine 11--pyrite 11- -pyrite 4.78 4.78 Mercur M e r c u r Hill H i l l mine mine 12--barite 12- -barite 3.73 3.73 Geyser-Marion G e y s e r - M a r i o n mine mine 13--pyrlte 13- -pyrite 9.87 9.87 Sacramento S a c r a m e n t o mine mine 14--stibnlte 14- - s t l b n i t e 10.12 10.12 Geyser-Marion G e y s e r - M a r i o n mine mine 15--pyrlte 15- -pyrite 17.12 17.12 Sacramento S a c r a m e n t o mine mine 16--barite 16- - b a r i t e 2.88 2.88 Mercur M e r c u r Hill H i l l mine mine 17--alunite 17- -alunite 2.60 2.60 G e y s e r - M a r i o n mine mine Geyser-Marion 18--jarosite 18- -jarosite 3.13 3.13 G e y s e r - M a r i o n mine mine Geyser-Marion 19--alunite 19- - a l u n i t e 2.64 2.64 G e y s e r - M a r i o n mine mine Geyser-Mar1.on 20--realgar 20- -realgar 10.29 10.29 Mercur M e r c u r Hill H i l l mine mine 67 6? a n d the the m o l a l i t i e s of o f potassium p o t a s s i u m and a n d sodium s o d i u m iions o n s in i n the the and molalities solutions. solutions. The T h e equilibrium e q u i l i b r i u m constants c o n s t a n t s are a r e mainly m a i n l y aa function f u n c t i o n of o f temperature, t e m p e r a t u r e , and a n d tthe h e activity a c t i v i t y coefficients coefficients oof f ttemper~ture e m p e r a t u r e and a n d tthe h e ionic i o n i c strength s t r e n g t h of o f fluids." fluids." More More s p e c i f i c a l l y Ohmoto O h m o t o (1972, ( 1 9 7 2 , pp.. 551) 5 5 1 ) bbelieves e l i e v e s that t h a t the the specifically a n d oxygen o x y g e n ffugacity u g a c i t y of o f a hhydrothermal y d r o t h e r m a l system s y s t e m can can pH and o m p o s i t i o n of o f the t h e mineral. mineral. ccontrol o n t r o l tthe h e oS3 < S s 4^ ccomposition 3 Jensen J e n s e n et. e t . ale a l . (1971a, ( 1 9 7 1 a , pp.. 624) 6 2 4 ) ppoint o i n t out o u t that that a n d S02 S0 ttend e n d tto o equilibrate e q u i l i b r a t e bby y tthe h e isotopic isotopic H2S and 2 exchange e x c h a n g e reaction: reaction: 4 + s3 2 0 + s32o ^H2SS3^ 3 2 + S3 4 J-. * H H2 S3 S + S ^002 2 ~ 3 2 2 3 2 2 Since S i n c e tthe h e ppredominant r e d o m i n a n t gas g a s ppresent r e s e n t at a t hhigh i g h temperatures temperatures i s S02 S0 and H a t low l o w temperatures, temperatures, H i s enriched enriched is and H2 SS at H2 SS is 32 344 i n S3 S^ a n d S02 S0 i n S3 S^ a s the t h e temperature t e m p e r a t u r e is i s lowered lowered in and in as 2 2 2 2 ( J e n s e n eet. t . al., a l . , 1971b, 1 9 7 1 b , p. p , 76). 76), (Jensen M g u r e 22 22 Figure i s Jensen's Jensen's is diagramatic d i a g r a m a t i c rrepresentation e p r e s e n t a t i o n of o f the t h e cchemical h e m i c a l reactions reactions taking t a k i n g pplace l a c e in i n a ffluid l u i d after a f t e r iit t hhas a s lleft e f t its i t s source. source. Some must S o m e considerations c o n s i d e r a t i o n s tthat hat m u s t bbe e taken t a k e n into i n t o account account in i n analyzing a n a l y z i n g the t h e Mercur M e r c u r sulfur s u l f u r isotopic i s o t o p i c data d a t a are a r e the the addition a d d i t i o n of o f sulfur s u l f u r from f r o m authigenic a u t h i g e n i c ppyrite, y r i t e , a sulfur sulfur bbearing e a r i n g mineral's m i n e r a l ' s formation f o r m a t i o n rrange, a n g e , the t h e pH and a n d oxygen oxygen fugacity f u g a c i t y of o f tthe h e hhydrothermal y d r o t h e r m a l solution, s o l u t i o n , the t h e temperature temperature o f tthe h e solution, s o l u t i o n , and a n d tthe he m i x i n g of o f ground ground w a t e r s with with of mixing waters jjuvenile u v e n i l e waters. waters. T h e ttwo wo m a i n ssources o u r c e s of o f sulfur s u l f u r rrepresent epresent The main i n the the in sulfur minerals s u l f u r bbearing earing m i n e r a l s are a r e bbelieved e l i e v e d to t o have h a v e come c o m e from from 68 68 (Medium T and Low P) S0 —>S0 (with same bS34 composition as HjS) 2 Orifice of fumarole 2 CO 4 H rigin of hypogene slllfates, sulfates, which SJ4 ich are enriched in s34 (derived from from H2S-->S02-~OJ)' h^S-OSO.,-*^), (derived while associated slllCides sulfides are co=paratively enrlched comparatively enriched 32 fro~ H H25) in SJ2 S (derived (derived from 2S) t 3H 2S0 3 -->::!2 S04+S+1l2 0 Origin of SOZ enriched in 5 34 (InClllence on tS)4 vallle of marine S04 oC +20.21..] 14 . variation increasing between 502 and H S with 2 increasing ti~e of equll ibration ~S Origin of early pyrite which in many many cases replaced by by ell, Zn, cases 1. is later later replaced Cu, Zn, and Pb. and Pb. Sulfide with little little if any Sulfide mineral. minerals with if any tSJ4 composition change change 1n in cS^ Indigenous ferric iron disseminated through rock HZS H22S0 2~OiC H,S to to SOZ' S02, H S033,, and and H H^O^ at 250*C 2S0 4 at gives SJ4 +16,+25, and +357.o +357.. s'A enrichments of +16,+25, respectively H.t. M S S02 respectively H.T. 2 M S+ZH O~->SO +)H 3H 2 2 2 2 2 sotoP1C equilibrium equi l1briulII occurring occllrring between bet ..·een Isotopic H and 50 SC> (aided by catalytic H2 H and (aided by catalytic H S and 2 2 H results in gradual increase H20 agents) reslllt. of SJ2 in H H2S and of 5S34 in SO2 S0 2 ~ 2 2 2 ? 3 2 34 2 ~:>H S32+S34 0 ) ((MH25, s +5+ s 0V 2 : > 2 s + s V2) 343 4 323 32 3 Ho (Hi P) (Hi TT and and Hi Hi P) H ^200 HZS CO ~ ":.~- ff::::;:o::::;",g ~u="" Parent magma or Rocks undergoing metamorphism •• H^O-CO^-H^S in in order order of of abundance ~02-H25 2 "ZS H S iiff pH pH << 77 2 HSpH>> 77 HS" iiff pH Figure Chemical S14 values F i g u r e 22. 22. C h e m i c a l rreactions e a c t i o n s aand nd values in i n aa ffuma.rolic u m a r o l i c conduit. conduit. ((from f r o m Jensen J e n s e n et. e t . al a l •• ., 1971, p. 77) 1971. P. 77) 669 9 waters. Jjuvenile u v e n i l e aand n d gground round w aters. The T h e aaddition d d i t i o n oof f sulfur sulfur was ffrom r o m hhydrocarbons y d r o c a r b o n s aand n d aauthigenic u t h i g e n i c ppyrite yrite w as probably probably minor m i n o r aand n d tthus h u s hhad a d vvery e r y llittle i t t l e eeffect f f e c t oon n tthe he ccomposition o m p o s i t i o n oof f tthe h e ssulfur u l f u r bbearing earing isotopic isotopic minerals. minerals. The T h e aauthor u t h o r bbelieves e l i e v e s tthat h a t tthe h e ssulfur ulfur isotopic isotopic was ccomposition o m p o s i t i o n oof f tthe h e ssamples amples w a s nnot o t ccontrolled o n t r o l l e d bby y pH aand n d ooxygen x y g e n ffugacity u g a c i t y bbecause e c a u s e tthe h e iisotopic s o t o p i c vvalues alues Ohmoto bby y O hmoto ((1972, 1 9 7 2 , pp.. 5559. 59, given given 5560, 6 0 , 5573) 7 3 ) ddo o nnot o t ffit i t tthe h e pH cconditions o n d i t i o n s bbelieved e l i e v e d tto o hhave a v e bbeen e e n ppresent resent hhydrothermal y d r o t h e r m a l aalteration. lteration. during during One O n e ccannot a n n o t eexpect x p e c t tthe he Table vvalues a l u e s oof f T a b l e 44 tto o rreflect e f l e c t ddirect i r e c t cchanging hanging isotopic isotopic equilibration equilibration conditions H2S c o n d i t i o n s bbetween etween H S aand n d S02 S 0 as a s in i n Figure F i g u r e 22. 22. 2 2 Since Since 4 and and Figure H2SS enriched iin n F i g u r e 22 2 2 one o n e considers considers H e n r i c h e d in i n s3 S ^ 3 2 3 22 S02 enriched in S3 at high temperatures and does not S0 at high of juvenile 2 enriched in S temperatures and does not consider the mixing of juvenile and ground waters at consider the moderate to mixing and moderate to low temperatures. low ground waters at temperatures. Mercur. Utah, represents a low temperature Mercur, Utah, represents a low temperature epithermal deposit. although high temperature conditions epithermal deposit, although high temperature conditions are believed to have existed in the intrusive magma. are believed to have existed in the intrusive magma. A convective hydrothermal system may have existed in and A convective hydrothermal system may h a v e ground water existed in and around the magma with the ground water being warmed and around the magma w i t h the being warmed and mixed with juvenile waters. In modern hot spring areas, mixed In modern with juvenile waters. hot spring oxygen isotopes indicate that most of the water is oxygen isotopes indicate that most of the water areas, is meteoric. Since rhyolites are believed to represent meteoric. Since rhyolites are believed to represent rocks of low water content, any water drawn towards and rocks of low w a t e r content, any water drawn towards and 70 70 into i n t o the t h e intrusive i n t r u s i v e would w o u l d help h e l p leach l e a c h the t h e rock r o c k as a s it it was w a s being b e i n g altered. altered. This mixing T h i s leaching l e a c h i n g and and m i x i n g oof f waters waters would w o u l d add a d d sulfur s u l f u r to t o the the waters. waters. Since S i n c e most m o s t of o f the t h e sulfur s u l f u r present p r e s e n t in i n tthe h e sulfides sulfides is i s bbelieved e l i e v e d to t o rrepresent e p r e s e n t sulfur s u l f u r from f r o m meteoric m e t e o r i c and and watprs, jjuvenile uvenile w a t e r s , any a n y heating h e a t i n g aand n d mixing m i x i n g of of w~ters with waters would w aters w i t h jjuvenile uvenile w aters w o u l d be be accompanied accompanied ratios bby y the t h e equilibration e q u i l i b r a t i o n of o f H2S H 2 S and a n d S02 S0 ratios according according 2 to T and t o existing existing T and P P conditions. conditions. meteoric meteoric At A t low l o w temperatures, temperatures, t h e conversion c o n v e r s i o n of o f S02 S 0 and a n d H2S H S in i n equilibrium e q u i l i b r i u m conditions conditions the 2 2 would, w o u l d , according a c c o r d i n g to t o Jensen J e n s e n et. e t , ale al. (1971b, ( 1 9 7 1 b t pp., 77). 77). 34 give composition: g i v e rrise i s e to t o sulfides s u l f i d e s differing d i f f e r i n g in i n S3 S composition: 4 S3 ~s34 + S 002 + + 3~ 3 % --. —* ftgS + 2H 2 H2 00 34 formed by the above reactions would add to the The H2S34 The H S formed by t h e above r e a c t i o n s would add t o t h e 32 H2 S enriched in S3 2 present in solution in near-surface, H S enriched in S present in solution in near-surface, low temperature conditions. 3 4 34 2 2 V 2 2 low t e m p e r a t u r e conditions. The differing degrees of alteration at Mercur The differing degrees of alteration at Mercur suggest that different physical and chemical environments existed there at one time. suggest that different Thus the physical and chemical existed there Thus at one physical time. and the chemical environments physical and chemical conditions that were present in one locality did not conditions that were present in one necessarily exist in a nearby area. necessarily exist in a nearby area. locality did not This situation This situation probably arose out of varying permeability conditions, probably arose out fracture plumbing of varying permeability conditions, plumbing control, nearness to the intrusive. fr~cture control, nearness to the intrusive, and the availability and ability of ground water to and enter the system. the availability These varying physical and chemical and ability of enter These varying physical the system. ground water and to chemical conditions would control the amounts of aqueous sulfur conditions would control the amounts of aqueous sulfur 71 71 species s p e c i e s that t h a t were w e r e ppresent r e s e n t and a n d thus t h u s the t h e isotopic isotopic composition c o m p o s i t i o n of o f tthe h e sulfur-bearing s u l f u r - b e a r i n g minerals. minerals. The T h e alunite a l u n i t e and a n d jjarosite a r o s i t e for f o r which w h i c h sulfur s u l f u r isotopic isotopic vvalues a l u e s were w e r e obtained o b t a i n e d bboth o t h show s h o w 08 6 S 34 ^ values v a l u e s nnear ear the the 3 4 primary os33 value. They are believed to be secondary primary <5S^ They and the result of as pyrite and value. are believed to be secondary and the result of the weathering of primary sulfides, the weathering such as pyrite and st1bnite. such of primary sulfides, stibnite. The orpiment and realgar from the Brickyard mine The orplment and r e4a l g a r from the Brickyard mine show a variation in oS33 4 which could 1ndicate mineral formation s h o w a v a r over i a t i o na period i n 6 S ^ of w h time i c h c owith u l d changing i n d i c a t e chemical mineral conditions f o r m a t i o n o or v e r acceptance a p e r i o d o fby t ithe m e mineral w i t h c h a nof g i nsulfur g c h e mwhose ical cisotopic o n d i t i o n scomposition o r a c c e p t a nwas c e determined b y t h e m i n e by ral pH o f and s u l foxygen u r whose fugacity i s o t o p i c cwhich o m p o saccording i t i o n w a s dto e t eOhmoto's r m i n e d b diagrams y pH a n d (1972, oxygen p. f u g 560, a c i t y 558) w h i c his a cunlikely. cording to p. 5 6 Barite 0, 558) 1 Ohmoto s diagrams (1972, samples 12 and 16 have a low is u n l i number kely. positive which B a r i toS34 e sam p l e s could n u m b e r indicate 12 a n d 1a 6 relatively h a v e a l o w high 2 temperature p o s i t i v e s S of w formation h i c h c o u l d since i n d i c a802 t e ais r eenriched l a t i v e l y inh i S3 gh 3 at high temperatures. temperature of 32 Alternatively, equilibrium formation since S0 2 is enriched in S v between H2 S and S02 may not have been reached during at high temperatures. Alternatively, formation of the barite. between H S and 2 S0 2 equilibrium Bar1te sample number 8 may 4 not have been reached during has a large positive os3 which could indicate a formation Barite of the barite. sample number primary origin in near-surface conditions. 34 has #14) a The l a r gstibnite e p o s i t i v(sample e 6S^ which 8 sample c o u l d has india c a t+10.12% e a value p r i m a r ywhich o r i g could i n i n nindicate e a r - s u r f aac ehotc ospring n d i t i o nenvironment s. or that T h e equilibrium s t i b n i t e ( s aconditions m p l e # 1 4 ) were s a m p l enot h a attained. s a +10.12# vPragenetic alue which or that relations c o u l d i n d for i c a t eth,! a htwo o t minerals s p r i n g e nin v i r hand o n m e nspecimen t equilibrium Pragenetic relations conditions for the were not two m i n e r a l s attained. in hand specimen 72 i n d i c a t e the t h e stibnite stibnite w a s deposited d e p o s i t e d in i n tthe h e later l a t e r stages stages indicate was of was o f bbarite a r i t e deposition d e p o s i t i o n or or w a s deposited d e p o s i t e d after a f t e r tthe h e barite. barite. Pyrite P y r i t e samples s a m p l e s number n u m b e r 11. 1 1 , 13. 1 3 $ and a n d 15 1 5 which which come come f r o m or o r nnear e a r tthe h e Sacramento S a c r a m e n t o mine m i n e show s h o w a change c h a n g e of of from ppositive o s i t i v e vvalues a l u e s which w h i c h could c o u l d rreflect e f l e c t ohanging changing chemical chemical conditions. condlt ions• 34 The deviations of 6S 34 values obtained could be The deviations of <5S^ values obtained could be explained by the non-equilibration of S02 and H2 S which explained by the non-equilibration of S0 and 2 H S 2 which was caused by the continuous addition of sulfur from was caused by ground waters. ground the continuous addition of sulfur from Also upwelling hot waters undergo waters. Also upwelling hot waters undergo changes in sulfur gas species content as the waters changes in sulfur gas species content as species are the waters are cooled and the sulfur gas species are oxidized. are cooled and the sulfur gas oxidized. Thus, the sulfur isotopic compositions of the dissolved gases are affected. Thus, the sulfur isotopic The isotopic compositions found compositions gases are affected. The isotopic of the compositions dissolved found are believed to represent the chemical conditions are believed to represent the chemical conditions commonly found in hot spring environments. commonly found in hot spring environments. SUMMARY AND AND RECOMMENDATIONS RECOMMENDATIONS The Mercur T h e ttrue r u e structural s t r u c t u r a l character c h a r a c t e r of of M e r c u r has h a s been been overlooked many o v e r l o o k e d for for m any ye~rs. years. The T h e rhyolite r h y o l i t e intrusive intrusive on o n the t h e north n o r t h side s i d e of o f Eagle E a g l e Hill H i l l appears a p p e a r s tto o have h a v e been been forcefully f o r c e f u l l y intruded i n t r u d e d and a n d tto o bbe e younger y o u n g e r than t h a n folding folding because b e c a u s e of o f tthe h e drag d r a g folds f o l d s tthat h a t occur, o c c u r , noticeably noticeably o n its i t s nnorth o r t h side. side. on T h e two t w o explosive e x p l o s i v e breccia breccia The pipes' pipes' f o r m a t i o n is i s bbelieved e l i e v e d tto o bbe e rrelated e l a t e d to t o the t h e hydrothermal hydrothermal formation activity which magmatic activity w h i c h was w a s a ppart a r t of o f end-stage end-stage m a g m a t l c activity. activity. T h e collapse c o l l a p s e bbreccia r e c c i a nnear e a r tthe h e ccenter e n t e r of o f the t h e ghost ghost The ttown o w n of o f Mercur M e r c u r formed f o r m e d at a t the t h e intersection I n t e r s e c t i o n oof f two two f a u l t s and a n d probably p r o b a b l y resulted r e s u l t e d from f r o m the t h e collapse c o l l a p s e of of faults t h e roof r o o f of o f aa solution s o l u t i o n cave. cave. the Alteration Great A l t e r a t i o n of o f tthe he G r e a t &lue B l u e Limestone L i m e s t o n e aand nd Eagle Hill E agle H i l l rhyolite rhyolite the the is i s low-grade l o w - g r a d e in i n the t h e area. area, Silicification with Sllicification w i t h some s o m e sericite s e r i c i t e and a n d illite i l l i t e is is charqcteristic c h a r a c t e r i s t i c of o f tthe h e gold g o l d oore r e sequence. sequence. Alteration Alteration of o f tthe h e Eagle E a g l e Hill H i l l rhyolite r h y o l i t e is i s varied v a r i e d and a n d includes includes kkaolinization, aolinization, sericitization, s e r i c i t i z a t i o n , and a n d silicification. sllicification. Kaolinization most K a o l i n i z a t i o n and a n d silicification s l l i c i f i c a t i o n are are m o s t prominent prominent tthe he in in intrusive i n t r u s i v e around a r o u n d the t h e Sacramento S a c r a m e n t o bbreccia r e c c i a pipe. pipe. Sericitization S e r i c i t i z a t i o n of o f the t h e groundmass g r o u n d m a s s of o f tthe h e intrusive i n t r u s i v e is is pprobably r o b a b l y llate-stage, a t e - s t a g e , deuteric deuteric alteration. alteration. The minerals T h e ggold o l d ore o r e sequence s e q u e n c e contains contains m i n e r a l s tthat h a t are are c h a r a c t e r i s t i c of o f an a n epithermal e p i t h e r m a l deposit. deposit. characteristic T h e gold gold The 74 74 mineralization with m i n e r a l i z a t i o n is i s associated associated w i t h oorpiment, rplment, realgar, realgar, galena, g a l e n a , arsenopyrite, a r s e n o p y r i t e , sphalerite, s p h a l e r i t e , chalcopyrite, c h a l c o p y r i t e , and and cinnabar. cinnabar. The T h e gold g o l d is i s invisible i n v i s i b l e even e v e n with w i t h tthe h e aid aid o f a reflecting reflecting m icroscope, of microscope. •, The T h e carbon-gold-arsenic c a r b o n - g o l d - a r s e n i c rrelationship e l a t i o n s h i p observed o b s e r v e d at at Mercur, Carlin, Mine, M e r c u r , Utah; Utah; C a r l i n , Nevada; N e v a d a ; aand n d Getchell Getchell M i n e , Nevada, Nevada, is i s an a n interesting i n t e r e s t i n g low l o w ttemperature e m p e r a t u r e rrelationship. elationship. rrelationship e l a t i o n s h i p is i s pprobably r o b a b l y ddue u e tto o hhydrothermal ydrothermal This This solutions solutions entering e n t e r i n g permeable p e r m e a b l e rreactive e a c t i v e bbeds e d s tthat h a t contained contained hydrocarbons. hydrocarbons. Organic O r g a n i c extraction e x t r a c t i o n pprocedures r o c e d u r e s applied applied to materials t o carbon-rich carbon-rich m a t e r i a l s from f r o m tthe h e tthree h r e e gold g o l d camps camps showed s h o w e d bby y the t h e use u s e of o f infrared I n f r a r e d spectroscopy s p e c t r o s c o p y tthe h e presence presence o f tthe h e alkane a l k a n e and a n d carbonyl c a r b o n y l groups. groups. of A l k a n e s aare re Alkanes of main o f tthe he m a i n constituents c o n s t i t u e n t s of o f ppetroleum. etroleum. one one Therefore, Therefore, some s o m e form f o r m of o f hydrocarbon h y d r o c a r b o n pprobably r o b a b l y served s e r v e d as a s the t h e source source for f o r the t h e carbon. carbon. Sulfur S u l f u r isotope i s o t o p e data d a t a for f o r tthe h e ssulfides u l f i d e s at a t Mercur Mercur 34 have a mean of +7.88 8S 34 and a spread of values have a mean of +7.88 6S^ and a spread of values which is characteristic of sulfur isotope data from which is other hot characteristic of other hot spring deposits. spring deposits. sulfur isotope data from isotope data The sulfur isotope data The sulfur are believed to reflect near-surface conditions, low are believed to reflect near-surface conditions, low temperature, and the continual mixing of ground waters temperature, and the continual mixing of ground waters with heated waters which resulted in H2 S-S0 2 disequilibrium. with heated waters which resulted in H S-S02 2 disequilibrium. Recommend~tions for further study include K-Ar dating Recommendations for further study include K-Ar dating of the Eagle Hill rhyolite intrusives at Ophir, Mercur. of the Eagle Hill rhyolite intrusives at Ophir, Mercur, West Mercur combined with chemical data on the intrusives West Mercur combined with chemical data on t h e intrusives 75 75 aat t each e a c h locality l o c a l i t y tto o ddetermine e t e r m i n e if i f they t h e y came c a m e from f r o m the the same s a m e ppluton. luton. Carbon C a r b o n isotope i s o t o p e data d a t a of o f the t h e carbon-rich carbon-rich mine zzone o n e at a t tthe h e Sacramento Sacramento m i n e might m i g h t bbe e of o f interest. interest. More M o r e pprecise r e c i s e identification i d e n t i f i c a t i o n of o f tthe h e organic o r g a n i c compounds compounds might m i g h t give g i v e ssome o m e clue c l u e aas s tto o tthe h e chemical c h e m i c a l and a n d temperature temperature conditions c o n d i t i o n s that t h a t existed e x i s t e d during d u r i n g tthe h e hydrothermal hydrothermal activity. activity. M o r e study s t u d y of o f tthf! h e sstructure t r u c t u r e outside o u t s i d e the the More M e r c u r area area m i g h t bbe e of o f interest. interest. Mercur might M o r e polished polished More s e c t i o n work work w i t h the t h e uuse s e of o f pproper r o p e r instrumentation instrumentation section with m i g h t bbe e uuseful s e f u l tto o tthe h e identification i d e n t i f i c a t i o n oof f gold g o l d occurrences occurrences might a n d relationships r e l a t i o n s h i p s with w i t h other o t h e r minerals. minerals. and SELECTED SELECTED REFERENCES REFERENCES Allen, R.H., Mill A llen, R . H . , 1910, 1 9 1 0 , Mines M i n e s and and M i l l of o f Consolidated Consolidated Mercur Eng. Min. M e r c u r Co.: Co.: E n g . and and M i n . Jour J o u r .•• , v. v . 89. 8 9 , n. n . 25, 25, pp.. 1273-1277. 1273-1277. Andrews. W.B., Mercur Mining A ndrews, W . B . , 1937, 1937. M e r c u r and a n d Manning Manning M ining Compass, v 1 7 . n. n . 3. 3 , pp.. 148-152. 148-152. Compass. v.. 17. Districts: Districts: Bissell. H.J Bissell, H . J .••, 1959. 1 9 5 9 . Geology G e o l o g y of o f tthe h e Southern S o u t h e r n Oquirrh Oquirrh Mountains Fivemile Pass--Northern M o u n t a i n s and and F ivemile P a s s — N o r t h e r n Boulter Boulter Mountain Counties. a n d Utah Utah C o u n t i e s , Utah: Utah: M o u n t a i n Area. A r e a , Tooele T o o e l e and Utah Mineralogical and M i n e r a l o g i c a l Survey S u r v e y Guidebook Guidebook U t a h Geological G e o l o g i c a l and Number N u m b e r 14. 1 4 , 269p. 269p. Butler. B . S . , 1920. 1 9 2 0 , The T h e Ore O r e Deposits D e p o s i t s of o f Utah: U t a h : U.S. U . S . Geo. Geo. B u t l e r , B.S., Survey p.. 387-395. S u r v e y Prof. P r o f . Paper P a p e r 111, 111, p 387-395. D e g e n s , E.T. Degens. E . T . and and H H.. Reuter, R e u t e r , 1964. 1 9 6 4 , Analytical A n a l y t i c a l Techniques Techniques in Field i n the the F i e l d of o f OrganiC O r g a n i c Geochemistry, G e o c h e m i s t r y , in i n Ingerson, Ingerson, E.. Adva.nces E., A d v a n c e s in i n Organic O r g a n i c Geochemistry: G e o c h e m i s t r y : New York, York, Pergamon Press. p.. 377-415. 377-415Pergamon P ress, p Ehlmann, E h l m a n n , A.J A . J .••, 1958, 1 9 5 8 , Pyrophyllite P y r o p h y l l l t e in i n Shales S h a l e s of. o f North North Central Utah: Unpublished Central U tah: U n p u b l i s h e d thesiS, t h e s i s , Univ. U n i v , of o f Utah. Utah, pp.. 64-79. 64-79. Emmons, Becker. S . F . and a n d G.F. G.F. B e c k e r , 1885, 1 8 8 5 . Camp C a m p Floyd F l o y d District, District, E m m o n s , S.F. in Precious i n Statistics S t a t i s t i c s and a n d Technology T e c h n o l o g y of o f tthe he P r e c i o u s Metals: Metals: Tenth United T e n t h Census C e n s u s of o f tthe he U n i t e d States. S t a t e s , v. v , 1), 1 3 , p. p. 454-455. 454-455. Erickson, A.L Marrazino, U.. Oda, E r i c k s o n , R.L., R.L., A . L .•.. M arrazino, U O d a , and a n d W.W. W.W.. Janes, Janes. 1964, Exploration 1 9 6 4 , Geochemical Geochemical E x p l o r a t i o n Near N e a r the t h e Getchell Getchell Mine, Humboldt Nevada: U.S. M ine, H u m b o l d t County, County, N evada: U . S . Geo G e o •. . -Survey S u r v e y Bull. Bull. 1198-A, 1 1 9 8 - A , 26p. 26p. Franklin, V.. Miller, F r a n k l i n , W.J. W . J . and and V M i l l e r , 1938. 1 9 3 8 , Metallurgical Metallurgical Developments Utah: U.S. D e v e l o p m e n t s at a t Mercur, Mercur, U tah: U . S . Bureau B u r e a u of of Mines M i n e s Tech. T e c h . Paper P a p e r 588, 5 8 8 , 42p. 42p. Gemmell, The Floyd Mining G e m m e l l , R.C B . C •• . , 1897. 1897. T h e Camp Camp F loyd M i n i n g District District and Mercur Mines, Eng. a n d the the M ercur M i n e s , Utah: Utah: E n g . and a n d Min. M i n . Jour J o u r •• ., v. p.. 403-404; v . 63, 6 3 , n. n . 17, 17. p 4 0 3 - 4 0 4 ; 427-428. 427-428. Gilluly, G i l l u l y , J., J . , 1932, 1 9 3 2 , Geology G e o l o g y and a n d Ore O r e Deposits D e p o s i t s of o f the the Stockton and Fairfield Quadrangles. Utah: U.S. Stockton and F a i r f i e l d Quadrangles, Utah: U . S . Geo. G e o . Survey S u r v e y Prof. P r o f . Paper P a p e r 17). 1 7 3 , 171p. 171p- ?? 77 Hausen, Hausen, at at of of p. p. D.M D . M•.. aand n d P.K. P . K . Kerr, K e r r , 1968, 1 9 6 8 , Fine F i n e Gold G o l d Occurrence Occurrence Carlin, C a r l i n , Nevada: N e v a d a : in i n Ridge, R i d g e , J.D., J . D , , Ore O r e Deposits Deposits t h e United U n i t e d StateS71933-1967: S t a t e s , 1 9 3 3 - 1 9 6 7 : New York, Y o r k , AlME, AIME, the 908-940. 908-940. Heikes, He i k e s , V.C., V . C . , 1920, 1 9 2 0 , Camp C a m p Floyd F l o y d or o r Mercur M e r c u r District. D i s t r i c t , in in B.S. B . S , Butler. B u t l e r , The T h e Ore O r e Deposits D e p o s i t s of o f Utah: U t a h : U.S. U.S. Geo. G e o . Survey S u r v e y Prof. P r o f . Paper P a p e r 111, 1 1 1 , p. p , 382-387. 382-387. Helgeson, H e l g e s o n , H.C. H . C . and a n d R.M. R . M . Garrels, G a r r e l s , 1968, I 9 6 8 , Hydrothermal Hydrothermal Transport T r a n s p o r t and a n d Deposition D e p o s i t i o n of o f Gold: G o l d : Econ. E c o n . Geo., Geo., v. v . 63. 6 3 , p. p . 622-635. 622-635. Hill, Floyd H i l l , V.C., V . C . , 1894, 1 8 9 4 , Ore O r e Deposits D e p o s i t s of o f Camp Camp F l o y d District, District, Tooele T o o e l e County, C o u n t y , Utah: U t a h : Proc. P r o c . Colo. C o l o . Sci. S c i . Soc S o c •• . , v. v . 5, 5, p. p . 54-65. 5^-65. Howard, H o w a r d , L.O., L . O . , 1913a, 1 9 1 3 a , Treatment T r e a t m e n t of o f Mercur M e r c u r Dumps: D u m p s : Salt S a l t Lake Lake Min. M i n , Re R e vv ., . , v. v . 15 1 5 ,, n. n . 8, 8 , p .• 17 1 7-19 - 1 9 •. 1913b, 1 9 1 3 b , History H i s t o r y of o f Milling M i l l i n g at a t the t h e GeyserGeyserMarion M a r i o n and a n d the t h e Sacramento: S a c r a m e n t o : Salt S a l t Lake L a k e Min. M i n . Hev., Rev., v. v . 15, 1 5 . nn.. 9, 9, p. p , 9-13. 9-13. 1913c, History 1913c, H i s t o r y of o f Cyaniding C y a n i d i n g at a t Sunshine: Sunshine: Salt Hev., S a l t Lake L a k e Min. Min. R e v . , vv.. 15, 1 5 , nn.. 10, 1 0 , p. p . 11-16. 11-16. 1913d, Modern 1913d, M o d e r n Flotations F l o t a t i o n s Debt D e b t to t o Sunshine: Sunshine: S a Il tt Lake Lake M in. R 1 5 , n. n . 11. 1 1 , p. p . 13 1 3-16 - 1 6 •. Sa Min. Hee vv ". , vv.. 15, 1913e, Dip, 1 9 1 3 e , Cyaniding C y a n i d i n g oon n the t h e West West D i p , Mercur: Mercur: S a l t Lake Lake M in. R e v . , v. v . 15. 1 5 , nn.. 12, 1 2 , pp.. 13-16. 13-16. Salt Min. Hev., M.L JJensen, ensen, M . L .•• , 1967, I 9 6 7 . Sulfur S u l f u r IIsotopes s o t o p e s aand n d Mineral Mineral Genesis, Barnes Geochemistry G e n e s i s , iin n B a r n e s ,• G e o c h e m i s t r y of o f Hydrothermal Hydrothermal Ore DeposIts: New Y York, Holt Rinehart O re D e p o s i t s : New ork, H olt R i n e h a r t aand n d Winston, Winston, IInc n c .•• , pp.. 143-165. 143-165. ____~--_____ R R.P. Ashley, Albers, .P. A s h l e y , aand n d JJ.P. .P. A l b e r s , 1971a. 1971a, Primary Secondary P r i m a r y aand nd S e c o n d a r y Sulfates S u l f a t e s at a t Goldfield, G o l d f i e l d , Nevada: Nevada: Econ. Geo E con. G e o •• . , vv.. 666, 6 , pp.. 618-626. 618-626. ana, ----~~~---e S S.. O Oana. N a k a i , aand nd G e s s a u , 1971b. 1971b, N.. N Nakai. G.. D Dessau. Sulfur Geochemistry Volcanic S u l f u r IIsotopic sotopic G e o c h e m i s t r y oof f V o l c a n i c and and Soc. Min. Geo. FFumarolic u m a r o l i c FFluids: luids: S oc M in. G e o . JJapan, a p a n , Spec. Spec. IIssue s s u e 22,, pp.. 76-79. 76-79. The Occurrence Gold JJoralemon. o r a l e m o n , PP., . , 1951, 1951. T he O c c u r r e n c e oof f G o l d aat t Getchell Mine, Nevada: Hcon. Geo., G etchell M ine, N evada: E con. G e o . , vv.. 446, 6, 2267-310. 67-310. the the p. p. 78 78 King, Wilson, K i n g , W.H. W . H . and a n d S.R. S.R. W i l s o n , 1949, 1 9 ^ 9 . Diamond-Drill D i a m o n d - D r i l l an an A u g e r Sampl1ng S a m p l i n g of o f Vanadiferous V a n a d l f e r o u s Shale, S h a l e , Mercur Mercur Auger Dome Mine, Utah: M i n e , Tooele T o o e l e County, County, U t a h : U.S. U . S . Bureau B u r e a u of of M ines R e p t . of o f Inv. I n v . 44572, 5 7 2 , 8p. 8p, Mines Rept. Lenzi, Reconnaisance L e n z i , G.W., G . W . , 1971, 1 9 7 1 # Geochemical Geochemical R e c o n n a i s a n c e at a t Mercur, Mercur, Utah: U t a h : Unpublished U n p u b l i s h e d Master's M a s t e r ' s tthesis, h e s i s , Univ. U n i v , of o f Utah, Utah, 51p. 51p. Mabey. M a b e y , D.R D . R .... , M.D. M . D . Crittenden. C r i t t e n d e n . Jr., J r . , H.T H . T .•. . . Morris. Morris, R.J. Roberts, R .J. R o b e r t s , and a n d E.W. E . W . Tooker, T o o k e r , 1964, 1 9 6 4 , Aeromagnetic Aeromagnetic and Map Part a n d Generalized G e n e r a l i z e d Geologic Geologic M a p of of P a r t of o f NorthNorthCentral U t a h : U.S. U . S . Geo. Geo. S u r v e y Geophys. G e o p h y s . Inv. Inv. Central Utah: Survey M a p GP-422. GP-422. Map Maguire, Romance M a g u i r e , D., D , , L.O. L . O . Howard, H o w a r d , 1913a, 1 9 1 3 a , The The R o m a n c e of o f aa Salt Lake Min. Rev., Famous Mine: F a m o u s Gold Gold M ine: S alt L ake M in, R e v , , vv.. 15. 15, nn.. 6, 6 , pp.. 13-17. 13-17. and a n d L.O. L . O . Howard. H o w a r d , 1913b, 1 9 1 3 b , The T h e Romance R o m a n c e of o f aa Min. ----=Pa-m-o-u-s-Gold lIUne: Famous Gold M i n e , Salt S a l t Lake Lake M i n . Rev., R e v . , vv.. 15. 15. nn.. 7, 7 . pp.. 9-15. 9-15. Mart1n. Mercur Has New H HOpes: Eng. Martin, G G •• . , 1934, 193^. M ercur H a s New opes: E n g . and a n d Min. Min. Jour., J o u r . , v. v . 135. 1 3 5 . nn.. 10. 1 0 , pp.. 446-447. 446-447. Merwin. R.W., Gold Resources Merwin, R . W . , 1968, 1968, G old R e s o u r c e s in i n the t h e Oxidized O x i d i z e d Ores Ores and a n d Carbonaceous C a r b o n a c e o u s Material M a t e r i a l in I n the t h e Sedimentary Sedimentary Beds Northeastern Nevada: B e d s of of N ortheastern N e v a d a : U.S. U . S . Bureau B u r e a u of o f Mines Mines Tech. Prog. T ech. P r o g . Rept. R e p t . 1, 1 , 16p. 16p. Moore, W.J., A Summary M oore, W . J . , 1973. 1973. A S u m m a r y of o f Radiometric R a d i o m e t r i c Ages A g e s of of Igneous Rocks Mountains, Igneous R o c k s in i n tthe h e Oquirrh Oquirrh M o u n t a i n s , North North Central Rcon. 97-101. C e n t r a l Utah: Utah: E c o n . Geo G e o •• . , v. v . 68. 6 8 , pp.. 97-101. Nichols, L.. PPeterson. N i c h o l s , I.L. I . L . aand nd L e t e r s o n , 1970. 1 9 7 0 , Leach1ng L e a c h i n g GoldGoldBear1ng Mill Tailings From Mercur, Utah: B e a r i n g M i l l T a i l i n g s From M e r c u r , U t a h : U.S. U.S. B u r e a u of o f M1nes M i n e s Rept. R e p t . 'Df o f IInv. n v . 7395. 7 3 9 5 , lOp. lOp. BUreau Ohmoto. O h m o t o , H., H . , 1972, 1 9 7 2 , Systemat1.cs S y s t e m a t i c s of o f Sulfur S u l f u r and a n d Carbon Carbon Isotopes in Hydrothermal are Deposits: Econ. I s o t o p e s i n H y d r o t h e r m a l Ore D e p o s i t s : E c o n . Geo., Geo., p.. 551-578. vv.. 67. 6 7 . nn.. 5. 5. P 551-578. Ong, V.W. Natural O n g , H.L H . L .•.. aand nd V . W . Swanson, S w a n s o n , 1969, 19^9, N a t u r a l Organic Organic Ac1ds 1n the Transportation. Deposition, A c i d s i n t h e T r a n s p o r t a t i o n , D e p o s i t i o n , and and Concentrat1on Gold: C o n c e n t r a t i o n of of G o l d : Colo. C o l o . School S c h o o l M1nes M i n e s Quart., Quart,, v. v . 64, 6 4 , nn.. 1, 1 , p. p . 395-4250 395-^25. 79 79 Palmer, L.A., Palmer, L . A . , 1909, 1 9 0 9 , Milling M i l l i n g Practice P r a c t i c e at a t tthe h e Consolidated Consolidated Mercur: Lake Min. M e r c u r : Salt Salt L ake M i n , Rev., R e v , , v~ v . 10, 1 0 , n. n . 23, 2 3 , pp., 15-17. 15-17. Radtke. A.S. B.J. Radtke, A . S . and and B . J . Scheiner, S c h e l n e r , 1970, 1 9 7 0 , Studies S t u d i e s of of Hydrothermal Deposition Carlin H y d r o t h e r m a l Gold Gold D e p o s i t i o n (I). (I). C a r l i n Gold Gold Deposit. Nevada: Role Deposit, N e v a d a : The The R o l e of o f Carbonaceous Carbonaceous Materials Bcon. M a t e r i a l s in i n Gold G o l d Deposition: Deposition: E c o n , Geo., Geo., v . 65. 6 5 , pp.. 87-102. 87-102. v. Roberts, A.S. Radtke, R o b e r t s , R.J R . J .•• , A .S. R a d t k e , and a n d R.R. R . R . Coats. C o a t s , 1971, 1971, Gold-Bearing North Central G o l d - B e a r i n g Deposits D e p o s i t s in in N orth C e n t r a l Nevada Nevada and a n d Southwestern S o u t h w e s t e r n Idaho: I d a h o : Econ. E c o n . Geo., G e o , , v. v , 66, 6 6 , p. p. 14-33. 14-33* Scheiner, S c h e i n e r , B.J., B . J . , R.E. R . E . Lindstrom, L i n d s t r o m , aand n d T.A. T . A . Henrie, H e n r i e , 1968, 1968, I n v e s t i g a t i o n of o f Oxidation O x i d a t i o n Systems Systems F o r Improving Improving Investigation For G o l d Recovery R e c o v e r y From F r o m Carbonaceous C a r b o n a c e o u s Materials: M a t e r i a l s : U.S. U.S. Gold B u r e a u oof f Mines M i n e s Tech. T e c h . Prog. P r o g . Rept. R e p t . 2, 2 , 8p. 8p. Bureau R.E. R . E . Lindstrom, L i n d s t r o m , and a n d T.A. T . A . Henrie, H e n r i e , 1969, 1969. Electrolytic E l e c t r o l y t i c Oxidation O x i d a t i o n oof f Carbonaceous C a r b o n a c e o u s Ore O r e for for Improving G o l d Recovery: Recovery: U . S . Bureau B u r e a u of o f Mines Mines Improving Gold U.S. T e c h . Prog. Prog. R e p t . 88,, 12p. 12p, Tech. Rept. R.E W.J Gray, R . E .•.. Lindstrom, Lindstrom, W . J •. ..G r a y , and a n d D.G. D.G. Peterson, Gold P e t e r s o n , 1972, 1 9 7 2 , Extraction E x t r a c t i o n oof f G o l d From F r o m Carbonaceous Carbonaceous Ore: U.S. O r e : Pilot P i l o t Plant P l a n t Studies: Studies: U . S . Bureau B u r e a u of o f Mines Mines R e p t . oof f IInv. n v , 7597, 7 5 9 7 . 20p. 20p. Rept. Spurr, EconomiC Geology S p u r r , J.E., J . E . , 1894-95, 1894-95. E conomic G e o l o g y of o f tthe h e Mercur Mercur Mining Utah: Annual M i n i n g District, District, U t a h : Sixteenth Sixteenth A n n u a l Report Report United oof f the the U n i t e d States S t a t e s Geological G e o l o g i c a l Survey, S u r v e y , Part P a r t II-II— Papers Economic P a p e r s of o f an an E c o n o m i c Character, C h a r a c t e r , pp.. 343-455. 3^3-^55• Zeller, Z e l l e r , R.P., R . P . , 1958, 1 9 5 8 , Paleocology P a l e o c o l o g y of o f the t h e Long L o n g Trail Trail Shale Member Blue Shale M e m b e r oof f tthe h e Great Great B l u e Limestone, L i m e s t o n e , Oquirrh Oquirrh R ange, U tah: B righam Y oung U n i v . Res. R e s . Stud.-Stud.-Range. Utah: Brigham Young Univ. G e o . Ser., S e r . , v. v . 55,. nn.. 8, 8 , 36p. 36p. Geo.