Experimental results of atomic absorption analyses for indium and thallium in 803 nonmagnetic concentrates from Alaska

The development in the U.S. Geological Survey of rapid methods for the determination by atomic absorption spectrophotometry of indium and thallium at limits of detection as low as 0.2 ppm each in geologic materials affords great advantages over spectrographic methods in studies concerned with values at or near the crustal abundances of these elements. Experimental application of the technique to the analysis of 803 nonmagnetic concentrates from Alaska showed specific disadvantages owing to the insolubility of cassiterite--one of the major sources for indium in concentrates--under the conditions of dissolution used in the preparation of samples for analysis by atomic absorption. Where nonmagnetic concentrates are used as a geochemical sample medium, and an exploration program is based on the interpretation of multi-element data, little purpose is served by independent analyses for indium and thallium.