Rho A, Red Buttes, East Kramer Borate area (East Kramer Colemanite area), East Kramer Mining District, San Bernardino County, California, USAi

Regional Level Types
Rho A	- not defined -
Red Buttes	- not defined -
East Kramer Borate area (East Kramer Colemanite area)	Area
East Kramer Mining District	Mining District
San Bernardino County	County
California	State
USA	Country

A B(borate)-As occurrence located in sec. 30, T11N, R6W, SBM, 6.0 km (3.7 miles) S of Red Buttes (coordinates of record) and 3.1 km (1.9 miles) N of Silver Peak [2] (Shadow Mountains) (7 miles E of Boron). Discovered in 1957. Owned by Tenneco Mining Inc. (1976- ). MRDS database accuracy for this location is not stated.

Mineralization is hosted in rocks of the Tropico Group, Tarqui Formation (clay, mud, claystone and sandstone). The ore body strikes NE and dips 5-15SE at a thickness of 78.33 meters with a depth-to-top of 320.04 meters and a length of 914.4 meters. The deposit is comprised of 2 ore bodies - the upper and lower zones. They are separated by 25 to 50 feet of shale and sandstone. Colemanite crystals are disseminated through the colemanite-bearing zones and in seamlets and beds averaging 0.25 inch (0.67 cm) thick. As minerals occur as discontinuous veins and patches in ore. The upper zone area is 7,200,000 square feet with a depth from surface to the middle of the zone of 775 to 1,100 feet and a thickness of 10 to 94 feet (50 foot average), a length/width of 3,000 by 2,400 feet. The lower zone area is 5,400,000 square feet and a depth from surface to the middle of the zone of 875 to 1,250 feet and a thickness of 0 to 93 feet (55 feet average), a length/width of 3,000 by 1,800 feet. The upper zone contains a sub-zone with a grade of 17% B2O3 that is 790 to 1,100 feet below the surface and 10 to 40 feet thick (24.6 feet average). Local rocks include Quaternary alluvium and marine deposits.

Analytical data results: The As content of the ore runs about 0.14% (1,400 ppm). The glass industry requires less than 287 ppm As in borates.

Reserve-Resource data are found in: Griswold, W.T. (1959); Evans, James R. and Anderson, T.P. (1976).

Reserves and resources: In-situ (estimate year = 1959): Total resources: 18,140,000 metric tons of ore. Commodity is B(borates) at 14 weight percent. In-situ (estimate year = 1976): Total resources: 9,070,000 metric tons of ore. Commodity is B(borates) at 9 weight percent.

The first 2 figures are estimated reserves broken out by upper and lower ore zones. The upper zone contains a sub-zone of 12,000,000 short tons of ore with a grade of 17% B2O3.

Other Databases

Link to USGS MRDS:	10023813

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References