Search U.S. government technical reports digitized or harvested by TRAIL.
Diamond drilling blast holes, Bell Mine, the Warner Co., Centre County, Pa.
Diamond-drilling blast holes, Bellefonte Mine, National Gypsum Co., Centre County, Pa.
Diamond-drilling blast holes, Eastern Magnetite Mine C
Blast-hole drilling with diamond drills at the Tennessee Copper Co. mines, Ducktown, Tenn.