User:Tillman/Cerro Colorado Mountains

thumb|'Cerro Colorado Mts from across Altar valley, 1959

The Cerro Colorado Mountains are a low mountain range in Pima County, Arizona. The highest point of the range is the Colorado Benchmark (5319 ft/1621 m), at coordinates 31.712041 N, 111.262048 W.

The Cerro Colorado Mine (Heintzelman Mine; Silver Queen Mine) was discovered around 1750 by Spanish explorers. The mine was in production from 1856 to 1884 and from 1901 to 1937. Early production was by the Sonora Exploration & Mining Company, which was then owned by Charles Poston and Samuel Colt. Production was some 3,000 tons of ore averaging about 100 oz. Ag/Ton, 0.1 oz. Au/Ton and minor amounts of Pb & Cu.

The richest ore on record ran over 12,000 oz. Ag per ton. The average ore mined in 1859 was 770 oz/t; the average of all ore mined since then has been about 225 oz/t. No significant quantities of ore were found below 350 feet.