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Washington District (Omega District), Nevada Co., California, USA

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NOTE: There is no USGS MRDS file for this district.

Location: A former Au-Cr-Cu-Ag-Pb-Zn mining area located in east-central Nevada County in the vicinity of the old mining town of Washington, 18 miles NE of Nevada City. It is in the south end of the Goodyear's Bar-Alleghany belt and includes the "diggings" at Alpha and Omega.

History: The Washington district was first mined during the gold rush, and the placers of the Middle Yuba River were highly productive. The Omega and Alpha hydraulic mines were opened in the middle 1850s and worked on a major scale through the 1880s. Later, Chinese miners reworked the tailings. Lode mining also began in the 1850s and continued steadily until about 1915. There was activity in the district again during the 1930s, and the Red Ledge mine has been worked in recent years. Baryte, chromite, and asbestos also have been mined here.

Geology: The district is underlain chiefly by slate, schist and quartzite of the Blue Canyon Formation (Carboniferous). A serpentine body one to two miles wide crops out in the central portion. The Relief Quartzite (Carboniferous) and amphibolite lie to the W and granodiorite to the E. The serpentine is a south extension of a belt that passes north-northwest through Alleghany and Goodyear's Bar in Sierra County. Tertiary andesite overlies the main ridges to the N and S.

Ore Deposits: The auriferous Tertiary channel gravels at Alpha and Omega are part of the main channel that extends west and north to Relief and North Bloomfield. Jarmin (1927) estimated that, at
Omega, 13 million cubic yards were mined and yielded 13½ cents (period values) in Au per cubic yard. Lindgren (1911) estimated that 40 million yards remained. The quartz veins contain small but rich ore bodies, similar to those of the Alleghany district to the north, but are not as plentiful. Except for arsenopyrite, sulfides are not usually abundant. A number of beautiful specimens of crystallized gold have been found in the Red Ledge mine. The Spanish mine also has yielded large amounts of

Mines: Lode: Giant King, Mexican Cons., Mount Hope, Red Ledge, Red Paint, St. Patrick, Spanish, Treasure Box. Placer: Alpha ($2 million +), Centennial, Omega, Phelps, and Yuba River.

Mineral List

Mineral list contains entries from the region specified including sub-localities

37 entries listed. 31 valid minerals. 1 (TL) - type locality of valid minerals.

Localities in this Region


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Irelan, William, Jr. (1888b), Eighth annual report of the State: California Mining Bureau. (Report 8), 946 pp.: 435-444.

Hobson, John B. (1890), Nevada, Placer, Siskiyou Counties: California Mining Bureau (Report 10): 10: 389-392.

Lindgren, Waldemar (1900), Description of the Colfax sheet, California: USGS Geological Atlas, Colfax folio (Folio No. 66), 10 pp.

Lindgren, Waldemar (1911), The Tertiary gravels of the Sierra Nevada of California: USGS Professional Paper 73, 226 pp.: 139-141.

MacBoyle, Errol (1919), Mines and mineral resources of Nevada County: California Journal of Mines and Geology, California Mining Bureau (Report 16): 16: 59-63.

Jarmin, Arthur (1927), Report of the Hydraulic Mining Commission upon the feasibility of the resumption of hydraulic mining in California: California Division of Mines 23rd Report of the State Mineralogist (Report 23): 112-115.

Averill, C.V. (1946), Placer mining for gold in California, Omega Mine, California State Division of Mines and Geology Bulletin 135, 336 pp: 265-266.

Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 545.

Clark, Wm. B. (1970a) Gold districts of California: California Division Mines & Geology Bulletin 193: 128.

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