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Porphyry Hill Mine, Mount Bullion, Bagby-Mariposa-Mount Bullion-Whitlock District, Mother Lode Belt, Mariposa Co., California, USA

Latitude: 37°28'30"N
Longitude: 120°1'20"W
A former lode Au mine located in sec. 20, T5S, R18E, MDM, 3.6 km (2.2 miles) SSE of Mount Bullion and 5.1 km (3.2 miles) WSW of Mariposa, on the SW flank of Negro Hill (close to Agua Fria Creek). Operated in 1901, 1905 & 1907-1910. MRDS database stated accuracy for this location is 1,000 meters. A former Las Mariposas land grant mine.

NOTE: MRDS database file #10109239 states that this locality is within Yosemite National Park. This is not true.

Local rocks include Quaternary glacial deposits.

Workings include unspecified underground openings. Workings could not be identified in 1954-1955.

Production information: Produced 37.97 tons of ore yielding $2,164.48, or an average of $57.09 per ton (period values).

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Bowen, O.E., Jr. & C.H. Gray, Jr. (1957), Mines and mineral deposits of Mariposa County, California: California Journal of Mines and Geology (Report 53): 53(1&2): 297.

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10109239 & 10115015.

U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0060430524.

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