Tooele County Gold Production
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OPHIR-RUSH VALLEY DISTRICT
The Ophir-Rush Valley (Stockton) district, in the central part of the west flank of the Oquirrh Mountains between the Camp Floyd district to the south and the Bingham district to the north, is known chiefly for lead, silver, copper, and zinc. Gold was recovered chiefly as a byproduct of the base-metal ores; total production through 1959 was about 104,000 ounces.
Silver deposits were found in 1864 in Rush Valley by soldiers of the California Volunteers stationed at a nearby military post known as "Camp Relief." Efforts at smelting the ore at first met with small success and the mines were abandoned by the end of 1865. After the Civil War the original claim owners, who were soldiers, were discharged and returned to their homes; however, mining laws were amended to make their claims permanently valid. This action retarded development of the district for several years (Gilluly, 1932, p. 117-118). Lead deposits were found in the Ophir area in 1865, but very little work was done on claims until 1870. Additional discoveries of silver-lead ores in the early 1870's in the Ophir and Rush Valley areas caused a brief period of prosperity that lasted until about 1880 at Ophir and until 1890 at Rush Valley (V. C. Heikes, in Butler and others, 1920, p. 363-366).
Beginning in 1904, production increased sharply. Zinc was first recovered from ores in the Ophir area in 1911 and from the Rush Valley mines in 1913. Activity has continued, with periodic fluctuations, through 1959.
Most of the exposed rock in the district consists of sedimentary formations that range in age from Cambrian to Pennsylvanian. The Cambrian rocks, about 2,500 feet thick, consist of the Tintic Quartzite at the base, the Ophir Formation, Hartmann Limestone, Bowman Limestone, and Lynch Dolomite. The Devonian System is represented by about 185 feet of Jefferson (?) Dolomite. Rocks of Mississippian age are the Deseret Limestone, Humbug Formation, and Great Blue Limestone. The Manning Canyon Shale is of Mississippian and Pennsylvanian age and is overlain by the Oquirrh Formation of Pennsylvanian age (Gilluly, 1932, p. 6-38). The rocks are folded into a northwest-trending anticline, the Ophir anticline, and are broken by fissures and faults, especially in the vicinity of Ophir Canyon, where a northeast-trending zone of faults has offset the axis of the Ophir anticline and the sedimentary beds about 2,000 feet. Northwest-trending normal faults are parallel to the west front of the Oquirrh Mountains (Gilluly, 1932, p. 69-74). Small intrusive stocks, dikes, plugs, and sills of monzonite, rhyolite, andesite, lamprophyre, and nepheline basalt cut the sedimentary formations.
The most important ore deposits are in the Honorine mine, just east of the town of Stockton. The ore bodies are in bedded replacement deposits in limestone beds of the Oquirrh Formation where these beds intersect faults or fissures. Primary ore consists of pyrite, galena, sphalerite, chalcopyrite, and arsenopyrite in a gangue of quartz and lime silicate minerals. Oxidized ore contains cerussite, plumbojarosite, jarosite, malachite, smithsonite, aurichalcite, pyromorphite, and limonite (Gilluly, 1932, p. 160-162). In the Ophir area, the chief deposits are in replacement bodies in Mississippian limestones, especially the Great Blue Limestone. A few deposits occur in the Ophir Formation and the Jefferson (?) Dolomite. With local exceptions, these deposits contain the same minerals as the replacement deposits in the vicinity of Stockton. Fissure veins occur throughout the district, but they are of little economic importance (Gilluly, 1932, p. 136-137).