The Hart or Castle Mountain mining district is in northeastern San Bernardino County about 15 miles east of Ivanpah near the Nevada border. Gold was discovered here in 1907, and the area flourished for a few years. For a time it was served by the Santa Fe Railroad's branch to Searchlight, Nevada. There was some activity again during the 1930s. The principal sources of gold were the Oro Belle, Valley View, and Hart Consolidated mines. The ore deposits consist of breccia zones along which the wall rock is silicified. The deposits contain pyrite and native gold in small grains and wires. Country rock consists of rhyolite flows, tuff, and breccia of late Tertiary age.
Hewett, D. F., 1956, Geology and mineral resources of the Ivanpah quadrangle, California and Nevada: U. S. Geol. Survey Prof. Paper 275, 172 pp.
Tucker, W. B., and Sampson, R. J., 1943, San Bernardino County, Valley View mine: California Div. Mines Rept. 39, p. 464.