Mineralogical Characterization and Purification of High-Purity Quartz from the Pegmatite Core Zone

Abstract

Pegmatitic quartz is an important source of high-purity quartz, and its purity and inclusion characteristics together constitute the key criteria for evaluating the efficient utilization of this quartz. This study takes the quartz resource from the core zone of a pegmatite deposit in Xinjiang as the research object, analyzing its process mineralogical characteristics and inclusion features, and conducting purification experiments. The results show that the mineral composition of the quartz resource from the core zone of the pegmatite in Xinjiang is simple, with the main mineral being quartz (~99%) with minor amounts of mica (<1%) and plagioclase (<1%). In-situ microanalysis indicates that the average contents of the four key impurity elements, Al, Ti, Li, and B, in the quartz are 13.24, 6.17, 0.10, and 2.55 μg/g, respectively, with a total average content of 22.49 μg/g, exhibiting a generally low abundance of impurity elements, which preliminarily suggests that the core-zone quartz of this pegmatite has the potential for preparing high-purity quartz. After a combined purification process involving physical separation, chemical leaching, and chlorination roasting, the total impurity content of the quartz samples decreased from 97.95 μg/g to 20.66 μg/g, corresponding to a purity of 99.9979%. Meanwhile, the fluid inclusion index decreased from 0.1362 to 0.0213, representing a total reduction of 84.36%, indicating that the combined purification process exhibits a remarkable removal effect on fluid inclusions. However, the Ti content in the purified samples remains relatively high (9.99 μg/g), which may limit its application in high-end optical, semiconductor, and other fields. In addition, the fluid inclusion index is not the sole indicator for evaluating the development degree of quartz inclusions, and further materialization evaluation is required to comprehensively assess the purification efficiency and guide process optimization.