Granite pegmatite quartz from Evje-Iveland: trace element chemistry and implications for the formation of high-purity quartz

Abstract

Previous studies imply that granite pegmatites and hydrothermal quartz veins are the most promising igneous repositories of high-purity quartz. This is because quartz from higher temperature geological settings (granites, monzonites. diorites etc.) accomodates higher concentrations of impurities in its atomic structure. Systematic studies of granite pegmatites from Evje-Iveland, South Norway, show a marked relationship between petrogenesis and the distribution of structural impurities. Accordingly, less fractionated pegmatites feature relatively high concentrations of Ti, Mg, Ca and Cr whereas more fractionated pegmatites contain higher concentrations of Fe, Li and B, and total concentration of structural impurities rises with the degree of differentation. Therefore, detailed knowledge of a pegmatite field, if combined with quartz analyses from a few carefully selected localities, may drastically reduce the area in which prospecting for high-purity quartz resources is feasible.