IRRADIATIVE COLORATION OF QUARTZ AND FELDSPARS WITH APPLICATION TO PREPARING HIGH-PURITY MINERAL SEPARATES

Visible discrimination of quartz and feldspars can be greatly facilita ted by the irradiative coloration of mineral concentrates using gamma- radiation from a Cs-137 source. Irradiated quartz samples typically be come smoky colored. Sanidine phenocrysts generally acquire a yellow co lor while plagioclase and plutonic K-feldspars respond weakly or negli gibly to irradiation. Manual separation of 0.25-3.0-mm mineral grains that were initially identical in appearance was readily accomplished f ollowing radiation treatment. Available data indicate that this proces s does not modify the chemical or isotopic composition of the sample.