Map of copper mines on U.S.-Mexico border, 1871
“California Gold Diggers, Mining Operations on the Western Shore of the Sacramento River,” lithograph published by Kellogg & Comstock, circa 1850
Hydraulic mining operation, North Bloomfield Mining and Gravel Company, Nevada County, California, 1870s.
Chinese miners working a sluice mining operation, Auburn Ravine, California, 1852
Chinese gold miner, California, 1850s
Miners coming out of mine shaft, Virginia City, Nevada, 1867.