Opals

Author:	Aitkens, Irene.
Year:	1931
Document Type:	USBI
Issuing Agency:	U.S. Dept. of Commerce, Bureau of Mines,
SUDOC:	C 22.11:6493
Series:	Information circular / Bureau of Mines ;
Report Number:	6493
Subject:	Opals
Link:	https://hdl.handle.net/2027/mdp.39015077576869