California · Sierra County
Producer

Sixteen-to-One Mine

Sierra County, California, United States
GoldSilver
⌖ Show on mapUSGS source ↗
Commodities
PrimaryGold
SecondarySilver
Commodity typeM
Deposit
Deposit typeHydrothermal vein
Model273: Low-sulfide Au-quartz vein
Orebody formTabular
Ore controlHigh-grade gold-bearing ore shoots are found within quartz veins, which fill fissures that cut the Paleozoic-Mesozoic crystalline basement. Favorable locations that controlled deposition of these ore shoots within the veins include changes in dip and strike, swellings, splitting, minor faulting, and junctions with other veins. Also important are locations where the veins encounter serpentinite. Some hydrothermal minerals in wall-rock aureoles adjacent to the veins contain minor gold.
Materials
Ore mineralsGold, Arsenopyrite, Pyrite
GangueQuartz, Ankerite, Sericite, Serpentine, Mica
Geology
Host rockAmphibolite,Schist · Feather River Peridotite Belt
Associated rockConglomerate,Serpentinite,Marble · Feather River Peridotite Belt
StructureAlleghany fracture system, Melones Fault Zone
Tectonic settingMagmatic arc
AlterationChloritic; chlorite, epidote \nSilicic; quartz, albite\nCarbonate; ankerite, sericite, chromium mica (?mariposite? in older literature)\nSteatization; talc\n\nExtensive carbonatization aureoles up to 10 feet thick are present adjacent to the veins in the Sixteen-to-One: chlorite schist, amphibolite, and serpentinite of the wall rock have been variously altered to ankerite, sericite, and chromium-mica, and quartz. \n\nOxidation is inconspicuous according to Ferguson and Gannett (1932).
Economic & production
Development statusProducer
Discovery year1896
Identification
Deposit ID10310678
Alternate namesOriginal Sixteen-to-One, Tightner, Ophir, Oriental, Rainbow, Twenty-One, Red Star, South Fork, Bald Mountian, Contract, Contract Extension, Eclipse
RegionNA
Data scoreA
Coordinates39.46498, -120.8434
References
Averill, C. V., 1942, Mines and minerals resources of Sierra County: California Journal of Mines and Geology, v. 38, no. 1, p. 17-48.Beard, J. S. and Day, H. W., 1987, The Smartville intrusive complex, Sierra Nevada, California: The core of a rifted volcanic arc: Geological Society of America Bulletin, v. 99, no. 6, p. 779-791.Bohlke, J.K., 1989, Comparison of metasomatic reactions between a common CO2-rich vein fluid and diverse wall rocks: Intensive variables, mass transfers, and Au mineralization at Alleghany, California: Economic Geology, v. 84, p. 291-327.Bohlke, J. K. and Kistler, R. W., 1986, Rb-Sr, K-Ar, and stable isotope evidence for the ages and sources of fluid components in gold-quartz veins of the northern Sierra Nevada foothills metamorphic belt, California: Economic Geology, v. 81, p. 296-322.Carlson, D. W., and Clark, W. B., 1956, Lode gold mines of the Alleghany-Downieville area, Sierra County, California: California Journal of Mines and Geology, v. 52, no. 3, p. 237-272.Clark, L. D., 1960, Foothills fault system, western Sierra Nevada, California: Geological Society of America Bulletin, v. 71, p. 483-496.Clark, W. B., 1966, Gold in Mineral resources of California: California Division of Mines and Geology Bulletin 191, p. 179-185.Clark, W. B., 1970, Gold districts of California: California Divisions of Mines and Geology Bulletin 193, p. 49-50.Clark, W. B., and Fuller, W. P., Jr., 1968, The Original Sixteen to One Mine: California Division of Mines and Geology Mineral Information Service, v. 21, no. 5, p. 71-75.Cooke, H. R., Jr., 1947, The Original Sixteen-to-One gold quartz vein, Alleghany, California: Economic Geology, v. 42, no. 3, p. 211-250.Coveney, R. M., Jr., 1981, Gold quartz veins and auriferous granite at the Oriental Mine, Alleghany, California: Economic Geology, v. 76, no. 8, p. 2176-2199.Day, H. W. and others, 1988, Metamorphism and tectonics of the northern Sierra Nevada, in Ernst, W. G., editor, Metamorphism and crustal evolution of the western United States (Rubey Volume VII): Prentice-Hall, Englewood Cliffs, New Jersey, p. 738-759.Ferguson, H. G., and Gannett, R. W., 1932, Gold-quartz veins of the Alleghany district, California: U. S. Geological Survey Professional Paper 172, 139 p.Harwood, D.S., 1988, Tectonism and metamorphism in the northern Sierra Terrane, northern California, in Ernst, W. G., editor, Metamorphism and crustal evolution of the western United States (Rubey Volume VII): Prentice-Hall, Englewood Cliffs, New Jersey, p. 764-788.Lindgren, W., 1895, Characteristic features of California gold quartz veins: Geological Society of America Bulletin, v. 6, p. 221-240.Logan, C.A., 1929, Sierra County: California Division of Mines 25th Annual Report of the State Mineralogist, p. 171-172.Marshall, B. and Taylor, B.E., 1981, Origin of hydrothermal fluids responsible for gold deposition, Alleghany district, Sierra Nevada, California: U.S. Geological Survey Open-File Report 81-355, p. 280-293.McKinstry, H. E., and Ohle, E. L., 1949, Ribbon structure in gold quartz veins: Economic Geology, v. 44, no. 2, p. 87-109.Saucedo, G. J. and Wagner, D. L., 1992, Geologic map of the Chico Quadrangle: California Division of Mines and Geology Regional Geologic Map Series Map No. 7A, scale 1:250,000.Weir, R. H. and Kerrick, D. M., 1987, Mineralogic, fluid inclusions, and stable isotope studies of several gold mines in the Mother Lode, Tuolumne and Mariposa Counties, California: Economic Geology, v. 82, p. 328-344.Wittkopp, R. W., 1979, Mercury-bearing metallic gold, Alleghany District, Sierra County, California: California Geology, v. 32, no. 1, p. 20-21.Wittkopp, R. W., 1983, Hypothesis for the localization of gold in quartz veins, Alleghany District, Sierra County, California: California Geology, v. 36, no. 6.Burke, J., 1997, Geology and current mining at the Original Sixteen-to-One Mine, Alleghany, California: Unpublished report, 11 p.