Some Mineralogical Applications for Investigations of Gold in Geological and Metallurgical Samples

In gold exploration and metallurgical testing, the role of the mineralogist is to assist in solving problems with regard to (a) sampling, (b) gold occurrences, and (c) petrologic classifications of host rocks. The presence of "coarse" gold as a sampling problem can be overcome by various methods, including "screen fire assays," screened analyses and special gravity techniques which may be used to determine distributions of "coarse" versus fine gold. Determinations of mineralogic associations of gold usually require special separation techniques, accompanied by fire-AA-mineralogic assays of the products. After accurate mineralogic analyses are obtained for various products, quantitative distributions of refractory gold associations can be calculated by the use of simultaneous equations. Petrologic classifications are required by the geologist for mapping and interpretation of the various rocks. After the petrology and mineralogic differences of the rock units are determined, x-ray diffraction analyses of analytical pulps can be used for lithologic logging of drill cores. XRD logging is an efficient method for correlating lithologic units and alteration trends throughout a gold prospect.