00870cam a2200253 4500 gs 68000344 DLC 20260227111423.0 690707s1968 dcua b 000 0 eng c gs 68000344 U.S. Geological Survey Library DLC DLC QE75 .P9 no. 612 QE516.N5 P36 Parker, Raymond L. (Raymond Laurence) Geochemistry of niobium and tantalum, by Raymond L. Parker and Michael Fleischer. Washington, U.S. Govt. Print. Off., 1968. iii, 43 p. illus. 29 cm. United States. Geological Survey. Professional paper 612 Includes bibliographies. Niobium. Tantalum. Fleischer, Michael, 1908- joint author. Geological Survey professional paper ; 612. 30543 30543