<p>Coupled dissolution-precipitation is one of the critical processes influencing the mineralogical and geochemical evolution of pegmatites. This mechanism involves the simultaneous dissolution of primary mineral phases and the precipitation of secondary phases, driven by changes in the chemical environment, often mediated by hydrothermal fluids. The Bailongshan Li deposit, located in the West Kunlun region of northwest China, is a significant geological formation known for its rich lithium content and associated rare metals such as tantalum, niobium, and tin. This study investigates the coupled dissolution-precipitation processes that have played a crucial role in the mineralization of this deposit, focusing on key minerals, including cassiterite (Cst), columbite-group minerals (CGM), and elbaite (Elb). Using a combination of petrographic analysis, back-scattered electron (BSE) imaging, cathodoluminescence (CL) imaging, and micro X-ray fluorescence (XRF) mapping, we examined the textural and chemical characteristics of these minerals. Our findings reveal intricate patchy zoning patterns and element distributions (indicated by the Nb, Ta, W, Mn, Fe, Hf, Ti for CGM; Hf, Ti Rb, W, Nb, Ta for Cst; Ti, Zn, Fe, W, Hf, Mn, K for Elb) that indicate multiple stages of mineral alteration driven by fluid-mediated processes. The coupled dissolution-precipitation mechanisms observed in the Bailongshan deposit have resulted in significant redistribution and enrichment of economically valuable elements. The study highlights the importance of hydrothermal fluids in altering primary mineral phases and precipitating secondary phases with distinct compositions. These processes not only modified the mineralogical makeup of the pegmatite but also enhanced its economic potential by concentrating rare metals. Signatures of coupled dissolution-precipitation processes can serve as an essential tool for mineral exploration, guiding the search for high-grade zones within similar pegmatitic formations.</p>