| Description |
The Rebel mine area includes about one-quarter of a square mile in central Beaver County, Utah. It lies in the northeastern end of the Star Range, in the Star (or North Star) mining district, five miles west of the town of Milford. Exposed sedimentary rocks consist of about 2000 feet of limestones, sandstones, and siltstones. The following units, named by Townsend (1953), were recognized: Rebel limestone, "unnamed" quartzite, and Williams limestone, from bottom to top. The Rebel unit consists of 1200 feet of recrystallized and bleached limestone. The "unnamed" quartzite is a silicified quartz sandstone which ranges in thickness from 160 to 550 feet. The Williams unit consists of at least 500 feet of limestone, very similar to the limestone of the Rebel unit. Along the western edge of the study area is a sequence of limestones, quartzites, and shales which is unrelated to the strata found in the rest of the area. This sequence appears to be separated from the Rebel limestone-Williams limestone sequence by a low-angle fault. Intrusive rocks of quartz-monzonite porphyry are present in the Rebel mine area as phacoliths, sills, dikes, a stock, and smaller apophyses. A little aplite and some dark inclusions of monzonitic composition were found in the porphyry. From field relationships, the following conclusions are drawn: (l) The intrusions were implaced at a relatively shallow depth. (2) The intrusions formed during or after folding and were intruded along zones of weakness formed by tensional stress at or near the crest of the major fold. (3) The surface rocks are probably underlain by a large "parent" intrusion. (4) The age of intrusion is probably Cretaceous but may be Tertiary. The features of contact metamorphism observed are (l) recrystallized and bleached limestones, (2) silicified sandstones, (3) skarns, (4) hornfels, and (5) veinlets of calc-silicate minerals, calcite, and quartz in the porphyry. The metamorphism proceeded as follows: 1) Large amounts of barren fluids exuded from the magma caused widespread recrystallization and bleaching of the limestones. 2) After solidification of at least the outer parts of the intrusions, a second, more limited, stage of fluids was exuded from the magma at depth. These cation-rich fluids rose through the permeable sandstone and siltstone beds, along tension fractures in the limestone, and along the limestone-porphyry contact, forming hornfels and skarns. 3) A third stage of fluids deposited malachite in cracks in the skarn minerals. However, these fluids were possibly not magmatic. Two basic types of skams are recognized, barren and ore-bearing The barren skams are composed of calc-silicate minerals only. The orebearing skarns have in addition the following ore minerals; specular hematite, magnetite, malachite, azurite, chalcopyrite, and scheelite. Folds, faults, and fissures are important in the Rebel mine area. The principal fold is a tight anticline which plunges about 65 degrees to the north. This fold localized the intrusions. Two NW-strikLng faults are cut by the N70E-striking Rebel fissure. It appears to be one of a large number of similar fissures which are found in the Harrington- Hickory mine area and the White Rock mine area. The larger of the two faults in the Rebel area is apparently the same fault which Townsend (1953) mapped as the East Fault in the Harrington-Hickory mine. At least 41 minerals, including the uncommon species ludwigite, clinohumite(?), and allanite, are present in the study area. Ore deposits are of both the contact metamorphic type and the fissure-filling type. The Rebel mine develops the fissure ore deposit. It was an important lead-silver producer in the 1870's. The ore consists of argentiferous galena and cerussite along with lesser amounts of iron, manganese, zinc, and copper minerals. Three factors appear to have controlled the deposition of ores the fissure, intersections of the fissure with pre-mineral faults, and limestone country rock. The potential of the Rebel mine as a future producer seems good. A systematic underground exploration program should be undertaken. An analysis of the Rebel dumps indicates a metal value of roughly 119,000 dollars in about 3500 tons* At this time the dump material is not ore. NOTE: Pull out diagram (PLATE 1A, 1B, 1C) oversized and is not included in this digitized version. |
