San Marcos Mine group (Pittsburg Harquahala Mine; Pittsburg Wilson Mine; Wilson Mine), Socorro Peak, Harquahala District, Harquahala Mts, La Paz Co., Arizona, USA
Latitude: 33°46'56"N
Longitude: 113°28'47"W
‡Ref.: Bancroft, H. (1911), Reconnaissance of the ore deposits in northern Yuma County, Arizona, USGS Bull. 451: 113-115.
Wilson, E.D., Cunningham, J.B., and Butler, G.M. (1934), Arizona Lode Gold Mines and Gold Mining (revised 1967), Arizona Bureau of Mines Bull. 137: 132.
Elsing, M.J. and Heineman, E.S. (1936) Arizona Metal Production, Arizona Bureau of Mines Bulletin 140: 104.
Keith, Stanton B. (1978) State of Arizona Bureau of Geology and Mineral Technology, Geological Survey Branch Bull. 192, Index of Mining Properties in Yuma County, Arizona: 153 (Table 4).
Arizona Bureau of Mines file data.
MRDS database Dep. ID file #10027606, MRDS ID #M003500; and, Dep. ID #10137475, MAS ID #0040120415.
A former underground Au-Ag-Fe-Cu mine located in North-central sec. 14, T5N, R12W, 4-5 road miles SE of Wenden, northern base of the Harquahala Mountains, on BLM-administered land. Started about 1897. Reopened 1915-1919. Owned at times, or in part, by the Salome Development Co.; Pittsburg Harqua Hala Gold Mining Co.; Pete Smith & Associates (1915-1919); Sibley; and, Worcester.
Mineralization is spotty, high-grade gold, with minor silver and copper ores, in the oxidized zone with quartz, brecciated wall rock and abundant iron oxides. The ore zone is 0.61 meters wide on average, strikes NE-SW and dips 30NW. Lenses of gold-bearing quartz and minor sulfides in depth, in lensing veins along a shear zone. Above the first level, the vein was 18 to 24 inches (45 to 60 cm) wide and contained high-grade Au ore. The vein pinches out and disappears in the roof on the first level. Only small lenses of gold-bearing quartz are at greater depth. Oxidation extends to the bottom of the mine.
The sheared Precambrian granite has been intruded by aplitic and basic dikes and is considerably faulted. The deposit occurs within the shear zone that strikes NE-ward & dips about 30ºNW.
Workings include an inclined shaft at 540 feet (164.59 meters), plus 1,200 feet of drifts on 4 levels (1909). This deposit was located in the late 1890's and was worked intermittently through 1934. It produced some 300 tons of ore averaging about 2.0 oz. Au/T and 0.3 oz. Ag/T, plus minor copper. Output through October, 1909 was some $12,400 of Au (period values).
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