Bunker Hill Mine

Amador County, California, United States

GoldSilver

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Commodities

PrimaryGold

SecondarySilver

Commodity typeM

Deposit

Deposit typeHydrothermal vein

Model273: Low-sulfide Au-quartz vein

Orebody formTabular, pinch and swell

Ore controlOre shoots within mesothermal gold-bearing quartz veins, and as disseminated auriferous sulfides in greenstone\n

Materials

Ore mineralsGold, Pyrite, Arsenopyrite

GangueQuartz, Slate, Calcite

Geology

Host rockSlate,Greenstone · Mariposa Formation

StructureMelones Fault zone, Bear Mountains Fault zone, Melones Fault zone

Tectonic settingMagmatic arc

AlterationWall rocks hydrothermally altered, having been partially to completely converted to ankerite, sericite, quartz, pyrite, arsenopyrite, chlorite, and albite. Locally, greenstone bodies adjacent to the quartz veins contain enough disseminated auriferous pyrite in large enough bodies to constitute low-grade ore.

Economic & production

Development statusPast Producer

Discovery year1852

Identification

Deposit ID10310594

Alternate namesRancheria Mine, Ranchoree Mine, South Mayflower Mine

RegionNA

Data scoreA

Coordinates38.42487, -120.8244

References

Carlson, D.W., and Clark, W.B., 1954, Mines and mineral resources of Amador County, California: California Journal of Mines and Geology, 50th Report of the State Mineralogist, p. 173.Clark, W.B., 1970, Gold districts of California: California Division of Mines and Geology Bulletin 193, p. 69-76.Duffield, W.A. and Sharp, R.V., 1975, Geology of the Sierra foothills melange and adjacent areas, Amador County, California: U.S. Geological Survey Professional Paper 827, 30 p.Knopf, A., 1929, The Mother Lode system of California: U. S. Geological Survey Professional Paper 157, 88 p.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.Logan, C.A., 1921, Amador County, Bunker Hill Mine: California State Mining Bureau, 17th Report of the State Mineralogist, p. 408-409.Logan, C.A., 1927, Amador County, Bunker Hill Mine: California State Mining Bureau, 23rd Report of the State Mineralogist, p. 157-158.Logan, C.A., 1934, Mother Lode gold belt of California: California Division of Mines Bulletin 108, p. 72-74.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.Storms, W.H., 1900, The Mother Lode region of California: California Mining Bureau Bulletin 18, p. 80.Tucker, W.B., 1914, Amador County, Bunker Hill Mine: California State Mining Bureau, 14th Annual Report of the State Mineralogist, p. 20-22.McDougall, B.W., 1929, Preliminary report on the Original Amador and Bunker Hill Mines, Amador County, California: Unpublished report, 13 p.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.Moore, L., 1968, Gold resources of the Mother Lode Belt, El Dorado, Amador, Calaveras, Tuolumne, and Mariposa counties, California: U.S. Bureau of Mines Technical Progress Report 5, p. 1-22