Diamond-drilling blast holes, Bellefonte Mine, National Gypsum Co., Centre County, Pa.

Author:	Mosier, McHenry.
Year:	1948
Document Type:	USBI
Issuing Agency:	U.S. Dept. of the Interior, Bureau of Mines,
SUDOC:	I 28.27:7438
Series:	Information circular / United States Department of the Interior, Bureau of Mines ;
Report Number:	7438
Subjects:	Blasting
	Rock-drills
	Boring machinery
	Diamond bits
	Mines and mineral resources--Pennsylvania--Centre--Equipment and supplies
Link:	https://hdl.handle.net/2027/mdp.39015077577453