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Show 108 Utah Academy of Sciences, Arts and Letters at the mouth near the floor of the first zone described. It begins slightly westward, of the open cut and appears to pitch very This zone while hill. the into parallel to the strike of the dike, of the open walls the on from the remnants quite irregular is seen across the fifteen feet of width to ten from pit to have occupied to have been and thickness vertical dike, six to eight feet of feet of length along the followed one hundred and twenty-five inconspicuous nearly three with strike into the hill. It is associated followed by the to have been seem that "feeders" horizontal muscovite, the beryl, that precipitated pneumatolytic mineralizers occurred most of the zone in which the is This columbite, etc. mus been produced and much of the nine tons of beryl that have all in "feeders" probability The nearly horizontal covite mica. which are partially ex main vertical channels are branches of euhedral quartz crystals, the dike. Here posed near the center of hematite turn coated with specular in are which coated with albite, crushed, pockety, and secondary iron-stained material, occupy tourmaline stringers black thinner nearly vertical zones paralleling but earlier than the massive which are later than the pink feldspar the feldspar but only par pink has replaced quartz. The quartz The latter forms residuals and tourmaline. the tially replaced extensions of and in parallel "islands" strung along the quartz as in the pink feldspar. tourmaline veins of position with the true conclusion that tentative the to Observations at the pit led the third one dis phase, albite-beryl-muscovite white the nearly latest phase in the development cussed In the foregoing, was the the microscopy of the samples from However, of the pegmatite. been an intermediate phase have taken, it appears that this may of pneumatolytic action before the stages dying developed during cooler solutions were deposited from the large masses of quartz from the pre muscovite the development of as a by-product of muscovite would be developed and Thus quartz existing feldspar. from potash feldspar and water: . . 3(K20.A1203.6SiO) + 2H20 -7 K20.3A1203.6Si02.2H20 + 2K20 + 12 Si02 quartz. plus potassiaplus Orthoclase plus water gives muscovite formed from feldspar Hence, for every molecule of silica liberated which usually there are twelve molecules of. muscovite of The extra potassia liberated quartz. crystallize out in the form and chemically very active tends to further soluble being very and hydrothermal solutions so that activate the pneumatolytic attacked and more potash feldspar are other aluminum silicates from which the muscovite is the feldspar If original developed. anorthoclase or other sodium-bearing formed happens to be then the excess soda (instead of feldspar, instead of orthoclase, or some other soda-rich feld albite form will potassia) liberated than one of the potash group. All the factors affecting rather spC!r conditions which determine whether muscovite and the equilibrium some |
