Microchemical tests for gold.
Crystals of gold pyridine double bromide. x250. Agfa color plate. Halftone by The Colorplate Engraving Co., New York, N.Y. Courtesy of G. P. Putnam, E. J. Roberts, and D. Selchow.
Illustrating M. N. Short, Microscopic determination of the ore minerals. Bulletin 914, U.S. Department of the Interior, Geological Survey. Second edition, 1940. (starts here)
29 December 2012
tags: determinations; indeterminate; lines; mind, states of; M. N. Short