Location
West flank of the Trigo Mountains. T. 2 S., R. 23 W.; Tps. 3 and 4 S., Rs. 23 and 24 W.
Topographic Maps
All 7 1/2-minute quadrangles—Picacho NW, Picacho, Cibola.
Geologic Map
Wilson, 1960, Geologic map of Yuma County, Arizona, scale 1:375,000.
Access
From Yuma, 71 miles north on State Highway 95 to Cibola Road, which leads 36 miles west to Cibola. One placer area is about 6 miles east of Cibola in the vicinity of the Hardt Gold mine, which is accessible by a dirt road. The Colorado River placers are about 13 miles south of Cibola and are accessible by a dirt road and jeep trial that parallels the river.
Extent
Small placers have been worked in drywashes in the Trigo Mountains for many years, but the location of these deposits is not described in the literature. Placers have been worked in drywashes south of the Hardt Gold mine in T. 2 S., R. 23 W., approximately sees. 1 and 2 (R. T. Moore, Arizona Bureau of Mines, oral commun., 1969).
Gold has been recovered from gravels along the west flank of the Trigo Mountains and possibly from Colorado River sands for many years. Very little information has been found about these deposits,which are located in the Paradise Valley section of the Colorado River Valley (Tps. 3 and 4 S., R. 24 W.).
Production History
Placers were mined in the Trigo Mountains as early as 1866, when placer activity was noted in the Silver subdistrict (T. 3 S., R. 23 W.). No estimate of early production is known. Placer-mining activity has been small scale throughout the 1900's and variously credited to the Trigo district and the Colorado River placers by the U.S. Bureau of Mines Minerals Yearbooks. Most of the placer gold was recovered from the Colorado River area, which was worked by many itinerant miners during the 1930's.
From 1950 to 1966, these deposits were mined yearly by dry concentration at the "Colorado River Valley property"; descriptions of the deposit and production from 1960 to 1966 is held confidential by the U.S. Bureau of Mines.
Source
Small gold-bearing quartz veins in fault zones in schists in the Hardt mine area have been worked at the Hardt mine, the Boardway prospect, and the Jupiter claims (all in the Cibola subdistrict). The Boardway prospect and the Jupiter claim, located south of the Hardt mine, probably represent the type of gold deposit from which the placers were derived.
Literature
Burchard, 1882: Notes placer activity in the Silver subdistrict in 1866.U.S. Bureau of Mines, 1950, 1951, 1953: Reports production from the "Colorado River Valley Property."
U.S. Bureau of Mines, 1950, 1951, 1953: Reports production from the "Colorado River Valley Property."
Wilson, 1933: Describes lode mines in Cibola region and other mines in Trigo Mountains.
