Location and History
This district is in northeastern San Bernardino County in the Clark Mountains about 35 miles northeast of Baker. Gold and other metals have been mined here since the early 1860s, and the mining district was organized in 1865. The mountains were named for Senator William A. Clark, the "copper king" of Montana. The gold mines were worked intermittently until the 1930s, and there has been prospecting since. The Mountain Pass mine located here is now an important source of rare earth minerals.
Geology and Ore Deposits
The district is underlain by a belt of limestone and dolomite in the central portion, with quartzite to the west and granite and gneiss to the east. The gold-bearing deposits consist of quartz and barite veins or mineralized breccia, the latter occurring in shear zones in gneiss that commonly are associated with rhyolitic dikes. The ore contains auriferous pyrite and chalcopyrite. Milling-grade ore usually averages 1/5 ounce of gold per ton. In this district the metal-bearing deposits are associated with major thrust zones that extend northward along the entire mountain mass.
Mines
Benson, Birthday, Colosseum, Green, Mohawk, Sulphide Queen, Taylor.
Bibliography
Hewett, D. F., 1956, Geology and mineral resources of the Ivanpah quadrangle, California and Nevada: U. S. Geol. Survey Prof. Paper 275, 172 pp.
Wright, L. A., Stewart, R. M., Gay, T. E., jr., and Hazenbush, G. C., 1953, San Bernardino County, gold: California Jour. Mines and Geol., vol. 49, pp. 69-86.
