Steele Mine (Steel deposit), Pilliken Mine (Pillikin Mine; Pillikan Mine; Pilliken Chrome Mine), Flagstaff Hill, Salmon Falls Mining District (Flagstaff Hill area), El Dorado County, California, USAi

Regional Level Types
Steele Mine (Steel deposit)	Mine
Pilliken Mine (Pillikin Mine; Pillikan Mine; Pilliken Chrome Mine)	Mine
Flagstaff Hill	Hill
Salmon Falls Mining District (Flagstaff Hill area)	Mining District
El Dorado County	County
California	State
USA	Country

A former Cr-Fe mine located in secs. 33 & 34, T11N, R8E, MDM, 0.5 km (1,600 feet) E of Flagstaff Hill and 2.0 km (6,500 feet) NW of Salmon Falls, on private (patented) land. Owned by A.B. Dobbs (surface rights) (100%), California (1976) and M. L. Harr, et al (1976) (mineral rights) (100%), California (1976). Operated by the Rustless Chrome Co. (1940-1942). First production occurred in 1914. Operated during the period 1914 to 1918. MRDS database stated accuracy for this location is 10 meters. One MRDS file indicates that this locality may now be inundated beneath the reservoir, but the topo map does not indicate this. MRDS file #10029651 states that "This is not the same area as is included in the holdings of the Pillikin Mine," while MRDS file #10163017 states "Part of the Pillikin Mine."

Mineralization is a Cr-Fe deposit hosted in dunite. The ore bodies are disseminated, tabular and lenticular, strike N45E and dip 75E at a thickness of 15 meters, width of 30 meters and a length of 90 meters (per USGS MRDS file #10163017). Ore body is irregular in form, strikes N55W and dips 50E at a thickness of 0.0 meters (sic), width of 30.48 meters and a length of 60.96 meters (per USGS MRDS file #10043725). Inverse nodular ore consisting of nodules of barren dunite contained in a matrix of nearly pure, disseminated chromite, is present in this deposit. The chromite deposits are discontinuous along the average strike. The deposit occurs in an elongate ultramafic mass exposed in the western metamorphic belt of the Sierra Nevada foothills. A thick mantle of slope wash and heavy vegetation covers much of the geology. The primary mode of origin was magmatic differentiation. Primary ore control was lithology and secondary was folding. Wallrock alteration is intense (carbonitization, silicification and bleaching). Local alteration included the serpentinization of peridotite. Associated rocks include lherzolite. Local rocks include ultramafic rocks, chiefly Mesozoic, unit 2 (Western Sierra Nevada and Klamath Mountains).

Workings include surface and underground openings comprised of open cuts, adits and prospect pits. Workings in 1918 consisted of 4 adits ranging in depth (sic) from 50 to 185 feet. Numerous small open cuts and pits are scattered over the area.

Production data are found in: Stinson (1976).

Reserves and resources: Type: in-situ; estimate year: 1918: inferred: 2,000 metric tons; total resources: 6,000 metric tons of ore. Cr2O3 @ 12 weight percent, Fe @ 12 weight percent. In 1918 both commodities were found as traces.

Cater estimated that the remaining ore averages no more than 10% Cr2)3. The Cr:Fe is unknown, but close to 1.6:1. Field office analysis by the Division of Mines & Geology in 1976 gave: massive ore: Cr2O3 @ 34.71%, FeO @ 12.34%, Total Fe @ 21.96%, Al2O3 @11.19%, MgO @ ??, Cr:Fe: 1.39; dissemionated ore: SiO2 @ 11.38%, Cr2O3 @ 31.06%, FeO @ 14.69%, Total Fe @ 24.12%, Al2O3 @ 6.63%, MgO @ 13.02%, Cr:Fe: 1.13.

Other Databases

Link to USGS MRDS:	10029651

Other Regions, Features and Areas containing this locality

References