The discovery and significance of pegmatite–type high–purity quartz deposits in the Shangnan of North Qinling, China

High-purity quartz is a critical strategic mineral resource for high-tech industries. While exploration of granitic pegmatite-type deposits has advanced in areas like the Altai and East Qinling Mountains, key scientific questions remain regarding the dense vein-type quartz deposits within Caledonian pegmatites of the East Qinling region. Specifically, it is unclear which types of pegmatites host high-purity quartz, what processes control quartz purity, and how mineralization differs from other pegmatite quartz systems. To address these questions, we conducted field surveys, detailed studies of mineralized veins, and geochemical analyses. The results show that high-purity quartz is primarily hosted in highly fractionated Li-Cs-Ta-type pegmatites, where intense albitization and late-stage fluid activity effectively removed impurity elements. Comparative analysis indicates that vein structure, mineral assemblages, and fluid evolution pathways differ significantly between mineralized and barren pegmatites. This study clarifies the metallogenic mechanism of dense vein-type high-purity quartz deposits and provides criteria for future exploration in the region.