Cerro Gordo District, Inyo Co., California, USA

This mining district lies near the summit of the Inyo Range, 5½ miles by air and 8 miles by a steep mountain road from Keeler, on the shore of Owens Lake. Discovered by Mexican prospectors in the early 1860's. Substantive production commenced in 1869 after Americans took over the area. Production was between $6.5 to $20 million (period values). Ores mined were initially lead-silver (argentiferous galena, and a little dark sphalerite). Rich ores mined in the early days consisted of lenticular masses of massive cerussite, 5 or 6 feet diameter, in the limestone. These masses were concentrically banded, and usually had a small core of unaltered galena. Tetrahedrite and Pyrite were prominent in the one primary vein. About 1911, zinc carbonate ores were discovered. The region consists of a series of westward dipping Carboniferous rocks (mainly limestone) with intrusive dikes of diorite and monzonite, nearly parallel to the bedding. An underlying mass of monzonite porphyry outcrops to the North of the mines.

References:
Merriam, Charles Warren (1963), Geology of the Cerro Gordo Mining District, Inyo County, California: USGS PP 408, 83 pp.

Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 49-50, 544.