Abstract

The Rush Valley (Stockton) district produced lead, silver, zinc, gold, and minor copper, commencing about 1866. The most significant production, from 1910-1954, was largely extracted through the Honerine drainage adit. After about 1910, the camp of Bauer at the mouth of the Honerine tunnel became the mining and metallurgical center of the district (and at times, the region), served by a spur from the D&RGW Railroad. Ore bodies typically were narrow zones at surface; several substantially increased in size at depth. Twelve thin, nearly vertical limestones separated by quartzite within the Pennsylvanian Oquirrh Group principally host the ores. The limestones can be correlated with similar members of the Lower Bingham mine and Butterfield Peaks formations. Several Late Eocene granitoids intrude these folded and faulted sedimentary rocks. The igneous bodies also increase in volume with depth. The largest unaltered bodies closely resemble the Last Chance monzonite stock of the nearby Bingham district. Drill holes and crosscuts also encountered sulfide-bearing porphyritic quartz monzonite with potassic and sericitic alteration. Calc-silicate alteration, consisting of fine-grained diopside and coarse wollastonite, evident at the present surface, apparently increase significantly with depth, judging from limited data from workings and drill holes. Veinlets of andradite garnet skarn suggest that skarn orebodies may exist at depth. The district is interpreted to be localized above a major igneous intrusive complex. Wall rock alteration is telescoped by the chemistry of host limestone and calcareous quartzite units. Deep sub-economic disseminated and fracture-controlled pyrite-chalcopyrite-gold mineralization has been documented in some intrusions. Tertiary volcanic rocks and nearby nepheline-bearing sills (undated) are probably coeval with the plutons of the district. Alteration zoning in carbonate and silicate sedimentary rocks around a deep, concealed porphyry copper system does not exhibit the concentric zoning of base metals found in non-limestone hosted districts.