Mine detail: Ophir District

Previously called 'numerous individual mines in this district'

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Location

Lat / long: 38.89111, -121.12278

Resource(M)

Primary: Gold, Silver
Secondary: Lead, Copper
Ore: Gold, Electrum, Pyrite, Chalcopyrite, Galena, Sphalerite, Arsenopyrite, Tetrahedrite, Molybdenite, Silver, Stibnite, Telluride
Gangue: Quartz, Calcite, Chalcedony
Orebody form: Tabular
Discovery year: 1851

Production

Operation type: Underground
Deposit type: Hydrothermal vein
Development status: Past Producer

Geology

Host rock:Penryn Pluton, Copper Hill Volcanics
Host type:Diorite,Amphibolite
Structure:Bear Mountains Fault Zone
Tectonic:Magmatic arc
Alteration processes:Carbonate; calcite, sericite, pyrite, minor chlorite; formed as selvages a few inches to a few feet wide in wallrock immediately adjacent to quartz veins.

References

DEP10310713
Reference{Deposit:: Clark, W.B. and Carlson, D.W., 1956, Mines and mineral resources of El Dorado County: California Division of Mines, California Journal of Mines and Geology, v. 52, p. 408.}{Deposit:: Clark, W.B., 1970, Gold districts of California: California Divisions of Mines and Geology Bulletin 193, p. 102-103.}{Deposit:: Clark. W.B., and Lydon, P.A., 1962, Mines and mineral resources of Calaveras County, California: California Division of Mines and Geology County Report No. 2, p. 40.}{Deposit:: Earhart, R.L., 1988, Geologic setting of gold occurrences in the Big Canyon area, El Dorado County, California: U.S. Geological Survey professional Paper 1576, 13 p.}{Deposit:: Hobson, J.B., 1890, Ophir Mining District: 10th Annual Report of the State Mineralogist, California State Mining Bureau, p. 426-434.}{Deposit:: Irelan, W., Jr.,, 1888, Auburn District: 8th Annual Report of the State Mineralogist, California State Mining Bureau, p. 460-462.}{Deposit:: Knopf, A., 1929, The Mother Lode system of California: U. S. Geological Survey Professional Paper 157, 88 p.}{Deposit:: Koschmann, A.H., and Bergendahl, M.H., 1968, Principal gold-producing districts of the United States: U.S. Geological Survey Professional Paper 610, 283 p.}{Deposit:: Lindgren, W., 1892, The gold-silver veins of Ophir, California: U.S. Geological Survey 14th Annual Report, Part 2, p. 243-284.}{Deposit:: Lindgren, W., 1894, Sacramento Folio: U.S. Geological Survey Atlas of the U.S., Folio 5, 3 p.}{Deposit:: Logan, C.A., 1927, Placer County: 23rd Annual Report of the State Mineralogist, California State Mining Bureau, p. 247-251.}{Deposit:: Logan, C.A., 1935, Placer County: 31st Annual Report of the State Mineralogist, California Journal of Mines and Geology, p. 17-18.}{Deposit:: Logan, C.A., 1936, Gold mines of Placer County: 32nd Annual Report of the State Mineralogist, California Journal of Mines and Geology, p. 28-31.}{Deposit:: Olmsted, F.H., 1971, Pre-Cenozoic geology of the south half of the Auburn 15-minute quadrangle, California: U.S. Geological Survey Bulletin 1341, 30 p.}{Deposit:: Schweickert, R.A., Hanson, R.E., and Girty, G.H., 1999, Accretionary tectonics of the Western Sierra Nevada Metamorphic Belt in Wagner, D.L. and Graham, S.A., editors, Geologic field trips in northern California: California Division of Mines and Geology Special Publication 119, p. 33-79.}{Deposit:: Wagner, D.L. and others, 1981, Geologic map of the Sacramento Quadrangle, California: California Department of Conservation, Division of Mines and Geology Regional Geologic Map Series, Map No. 1A, scale 1:250,000.}{Deposit:: Waring, C.A., 1915, Placer County: 15th Annual Report of the State Mineralogist, California State Mining Bureau, p. 318-319.}{Deposit:: Zimmerman, J.E., 1983, The Geology and structural evolution of a portion of the Mother Lode Belt, Amador County, California: unpublished M.S. thesis, University of Arizona, 138 p.}
ReporterSchruben, Paul G., Higgins, Chris T.