Minerals

High-purity quartz is an important raw material for strategic emerging industries, including photovoltaics and semiconductors. To improve the deep removal of impurities from granitic-pegmatite quartz and clarify the effects of calcination–water quenching, a quartz concentrate from the East Qinling Mountains was selected as the feed material. Calcination–water quenching, HF–HCl–HNO₃ mixed-acid leaching, and chlorination roasting were systematically investigated. The results showed that calcination temperature markedly affected quartz-sand whiteness and the occurrence of residue-like surface attachments. Treatment at 900 °C substantially reduced these attachments and enhanced subsequent acid-leaching efficiency. At final HF, HCl, and HNO₃ concentrations of 1, 2, and 1 mol/L, respectively, Al, Ca, Fe, K, Na, and other impurities were effectively removed, reducing the total concentration of 15 impurity elements to 19.43 μg/g. The inclusion area fraction decreased from 0.97% to 0.38%. Subsequent chlorination roasting at 900 °C further reduced the total impurity concentration to 17.26 μg/g, increased the nominal SiO₂ purity to 99.9982%, and decreased the inclusion area fraction to 0.31%. These results demonstrate the potential of East Qinling granitic-pegmatite quartz as a feedstock for photovoltaic-grade high-purity quartz sand.

Mining and metallurgical wastes contain potentially valuable mineral resources but pose growing environmental risks. This review proposes a mineralogy-guided framework for converting these wastes into low-carbon binders and construction materials. Rather than classifying residues by origin or bulk oxide composition, it distinguishes them according to the reaction roles of their mineral phases. The framework first distinguishes self-sufficient systems, in which activation unlocks the intrinsic mineral inventory of the waste sufficiently for matrix or product formation, from mineralogically compensated systems, in which additional functional mineral solids are required to supply deficient reactive Si, Al, Ca, sulfate, alkalinity, or other phase-forming components. Binary and multicomponent formulations are then interpreted according to the specific mineralogical functions supplied by the complementary solids and the resulting changes in reaction pathways and products. Thermal, hydrothermal, mechanochemical, alkaline, and carbonation-based processing routes are compared in relation to phase composition, co-precursor function, and the mechanical, thermal, and service properties of concretes, foams, and backfill materials. Evidence indicates that performance depends more on chemical complementarity than on maximizing waste content. Environmental benefits must also account for contaminant immobilization, carbon dioxide binding, and the energy and reagent demand of pretreatment. Mineralogy-informed machine-learning models may support inverse mixture design, but their transferability remains constrained by feedstock heterogeneity and limited standardized data. The framework links mineralogy, processing, reaction products, performance, and scale-up.

The Xianglin Sn polymetallic deposit, located on the northwestern margin of the Cuonadong dome in the eastern Tethyan Himalaya, represents an important Sn-W-Be polymetallic system recently recognized in southern Tibet. This study investigates the nature and evolution of the ore-forming fluids and the mechanisms of cassiterite precipitation. Fluid inclusion petrography, microthermometry, and laser Raman spectroscopy were applied to inclusions from the cassiterite–sulfide, proximal cassiterite–quartz vein, distal cassiterite–quartz vein, and late fluorite–quartz vein stages. The fluid inclusions mainly comprise liquid-rich, vapor-rich, H₂O-CO₂ three-phase, and minor daughter-mineral-bearing inclusions. The cassiterite–sulfide stage contains the most complex inclusion assemblage, with homogenization temperatures of 326–399 °C and salinities of 2.4–10.5 wt.% NaCl equiv. The proximal cassiterite–quartz vein stage yields homogenization temperatures of 280–361 °C and salinities of 2.4–9.6 wt.% NaCl equiv., whereas the distal cassiterite–quartz vein stage records lower temperatures of 195–295 °C. The fluorite–quartz vein stage is characterized by low-temperature and low-salinity fluids. Raman spectra identify CO₂, N₂, CH₄, H₂S, and CaCO₃ daughter minerals, indicating a volatile-rich, relatively reduced H₂O-CO₂-NaCl hydrothermal system. These features suggest that the principal ore-forming fluids were dominantly magmatic–hydrothermal fluids exsolved from highly fractionated Miocene leucogranites. During upward and outward migration from the main detachment zone to peripheral fractures, the fluids experienced boiling, cooling, mixing, and multistage hydrothermal overprinting. Cassiterite precipitation during the cassiterite–sulfide stage was mainly triggered by boiling or phase separation, whereas the proximal cassiterite–quartz veins were controlled by progressive cooling and local phase separation. In contrast, distal cassiterite precipitation was more strongly influenced by fluid mixing and cooling. These results indicate that the Xianglin deposit records a structurally controlled proximal-to-distal magmatic–hydrothermal Sn mineralizing system related to the Cuonadong dome.