Search U.S. government technical reports digitized or harvested by TRAIL.
Gold mining and milling in the Black Canyon area, Yavapai County, Ariz.
Placer operations of Humphreys Gold Corporation, Clear Creek, Colo.
Mining and milling methods and costs at the Summitville Consolidated Mines, Inc., Summitville, Colo.
Mining of feldspar and associated minerals in the southern Black Hills of South Dakota