The Wilson (Pine Grove, Rockland, Cambridge) district is in south-central Lyon County in parts of Tps. 9 and 10 N., Rs. 25 and 26 E. This district was in Mineral County until 1933, when a boundary change put it in Lyon County.
Gold was discovered in some outcrops in this area in 1866, and soon afterward the Wilson and the Wheeler mines were producing. The district produced steadily to 1893, and to that time the Wilson mine had produced ore valued at $5 million, and the Wheeler, $3 million (Hill, 1915, p. 136). Hill reported a production from 1902 to 1911 of $142,524 (about 7,000 ounces) in gold from the district. The Rockland mine produced $263,071 worth of ore during 1915-16 (Stoddard and Carpenter, 1950, p. 96). From 1917 through 1959 the district was idle except for a brief period of small-scale activity in the late 1930's and early 1940's. Total gold production through 1959 was about 408,000 ounces.
The district is underlain by quartz monzonite, very similar to that in the Sierra Nevada batholith (Hill, 1915, p. 134, 135). The ore deposits are in a sheared zone that crosses the quartz monzonite in a northwesterly direction. The quartz monzonite is also cut by at least one granite porphyry dike and is overlain by a series of pink and gray rhyolite flows.
The ore consists of lenses of quartz and pyrite in the crushed zone of monzonite just south of the major fault. The valuable constituents are gold and silver, and the highest grade ore is in the oxidized zone near the surface.
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