Search U.S. government technical reports digitized or harvested by TRAIL.
Placer mining in the western United States :part 1. general information, hand-shoveling, and ground-sluicing
Placer mining in the western United States :part II. Hydraulicking, treatment of placer concentrates, and marketing of gold
Placer mining in the western United States :part III. Dredging and other forms of mechanical handling of gravel, and drift mining
Copper Mining in North America