California · Mariposa County
Past Producer

Mary Harrison-Malvina Group

Mariposa County, California, United States
GoldSilverCopperLead
⌖ Show on mapUSGS source ↗
Commodities
PrimaryGold
SecondarySilver, Copper, Lead
Commodity typeM
Deposit
Deposit typeHydrothermal vein and replacement; hydrothermal stockwork
Model273: Low-sulfide Au-quartz vein
Orebody formTabular, irregular
Ore controlOre is present in a fissure-filling vein system along the Melones Fault Zone. The vein system is a complex characterized by ribbon-structured milky quartz with septa of slate as well as carbonate-type altered greenstone and serpentinite. According to Hehnke (1990), all significant gold mineralization in the Mary Harrison group is hosted by hydrothermally altered greenstone; high-grade mineralization is associated with brecciation and stockwork quartz-carbonate veining. Locally, high-grade mineralization is found in QAM rock adjacent to massive quartz veins and in association with swarms of porphyritic dikes.
Materials
Ore mineralsGold, Pyrite, Galena
GangueQuartz, Ankerite, Talc
Geology
Host rockSlate,Serpentinite,Schist · Mariposa Formation
StructureMain and subsidiary branches of the Melones Fault Zone
Tectonic settingMagmatic arc
AlterationAt the Mary Harrison group (from Hehnke, 1990, and Evans and Bowen, 1977):\n\nCarbonate; ankerite, quartz, sericite, Cr-mica, pyrite, albite (10-30% carbonate, up to 75% sericite, and < 2% albite all in greenstone; massive ankerite, 10-50% quartz veinlets, and several percent Cr-mica all in serpentinite). \nChloritic; chlorite, talc; all in serpentinite
Economic & production
Development statusPast Producer
Discovery year1852
Identification
Deposit ID10310708
Alternate namesMerced, Louise (Louisa), Potosi, Mahoney, Douglass, D. Cook
RegionNA
Data scoreA
Coordinates37.69417, -120.18444
References
Bowen, O.E., Jr. and Gray, C.H., Jr., 1957, Mines and mineral resources of Mariposa County, California: California Journal of Mines and Geology, v. 53, nos. 1-2, p. 35-343.California, in Seedorff, E., editor, Geology and ore deposits of the Sierra Nevada and foothills: Geological Society of Nevada, Special Publication No. 11, 1990 Fall Field Trip Guidebook, 134 p.Castello, W.O., 1921, Mariposa County: California State Mining Bureau, 17th Annual Report of the State Mineralogist, p. 86-143.Clark, W. B., 1970, Gold districts of California: California Division of Mines and Geology Bulletin 193, p. 41-42.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. 72-73.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.Evans, J.R. and Bowen, O.E., 1977, Geology of the southern Mother Lode, Tuolumne and Mariposa counties, California: California Division of Mines and Geology Map Sheet 36, scale 1:24,000.Hehnke, C.A., 1990, Geology and mineralization of the Mary Harrison prospect, Mariposa County,Julihn, C.E., and Horton, F.W., 1940, Mineral industries survey of the United States - Mines of the southern Mother Lode Region, Part II - Tuolumne and Mariposa counties: U.S. Bureau of Mines Bulletin 424, 179 p.Kistler, R.W., Dodge, F.C.W. and Silberman, M.L., 1983, Isotopic studies of mariposite-bearing rocks from the south-central Mother Lode, California: California Geology, v. 36, no. 9, p. 201-203.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.Landefeld, L.A., 1990, The geology of the Mother Lode gold belt, Foothills metamorphic belt, Sierra Nevada, California, in Landefeld, L.A. and Snow, G.G., editors, Yosemite and the Mother Lode gold belt: Geology, tectonics, and the evolution of hydrothermal fluids in the Sierra Nevada of California: American Association of Petroleum Geologists, Pacific Section, Guidebook 68, p. 117-124.Logan, C.A., 1935, Mother Lode gold belt of California: California Division of Mines Bulletin 108, 240 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.Newton, M.C., III, 1990, Structural control of gold mineralization in the southern Mother Lode region in Seedorff, E., editor, Geology and ore deposits of the Sierra Nevada and foothills: Geological Society of Nevada, Special Publication No. 11, 1990 Fall Field Trip Guidebook, 134 p.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.Wagner, D.L., Bortugno, E.J., and McJunkin, R.D., 1990, Geologic map of the San Francisco-San Jose Quadrangle, California: California Department of Conservation, Division of Mines and Geology Regional Geologic Map Series, Map No. 5A, scale 1:250,000.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.