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Jasper prospect, Keystone, Tuolumne Co., California, USA

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A Mn occurrence/prospect located in the NE¼ sec. 23 & in the NW¼ sec. 24, T1S, R13E, MDM, 0.9 km (2,800 feet) ENE of Keystone. Owned by E. M. Jasper, California (1974). MRDS database accuracy for this location is not stated.

Mineralization is a Mn deposit. Banded quartzite (probably metachert) is cut by quartz veins up to 6 inches (15 cm) thick. Manganese stains occur along fractures, and a 1 foot (30 cm) thick zone is partially penetrated by manganese oxides. The quartzite is enclosed in quartz mica schist which strikes N65W and dips 60NE. A serpentine belt lies ½ mile to the NE with green meta-volcanics containing manganese oxide stains along fractures. Rocks strike N40W and dip 70NE. Local rocks include Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains).

Workings include unspecified surface openings/operations.

Analytical data results: Probably less than 10% Mn.

Mineral List

1 entry listed.

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Trask, Parker Davies, Ivan F. Wilson & F.S. Simons (1943), Manganese deposits of California – a summary report: California Division Mines Bulletin 125: 207.

Trask, Parker Davies (1950) Geologic description of the manganese deposits of California. California Division of Mines Bulletin 152, 378 pp.: 344.

USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10033741 & 10141730.

U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0061090004.

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