THE DISTRIBUTION OF TRACE PRECIOUS METALS IN MINERALS AND MINERAL PRODUCTS

DATA on the distribution of the precious metals (Au, Ag and the platinum-group elements Ru. Rh, Pd. Os, Ir, Pt) are rapidly accumulating as a consequence of the application of microbeam analytical techniques such as the electron microprobe, the proton microprobe, and the ion microprobe. The new data obtained with these techniques build on knowledge accumulated over the last 140 years using bulk analytical methods (e.g. spectrographic). The nature of the occurrence, the concentrations, and the variation in amounts of precious metals in minerals and mineral products are reviewed with comments as to the significance of the results with respect to industrial and environmental concerns. Future directions in mineral-specific analysis of trace precious-metal concentrations and applications outside of process mineralogy are discussed.