The Mule Mountains district, which has also been known as the Hodges Mountain district, is in southeastern Riverside County about 20 miles southwest of Blythe. Some gold and copper were recovered here years ago from several mines and prospects, the most productive of which were the Roosevelt and Rainbow group of mines. Native gold, pyrite, and chalcopyrite occur in quartz veins in granitic rock.
Tucker, W. B., and Sampson, R. J., 1945, Riverside County, Roosevelt and Rainbow group of mines: California Div. Mines Rept. 41, pp. 142-143.