Abstract: High−purity quartz sand is an essential foundational material for strategic industries such as photovoltaics and semiconductors, where ultra−high purity and stability are strictly required. However, due to the scarcity of high−quality quartz resources in China, the supply of high−purity quartz sand has long been heavily dependent on imports, posing significant supply security risks and creating a critical bottleneck for industrial development. Among the various impurity types, inclusion impurities are particularly challenging, as they are encapsulated within the intact SiO₂ crystal lattice and exhibit extremely high chemical stability. As a result, they are difficult to remove using conventional physical and chemical purification methods and have become the primary constraint on achieving deep purification of high−purity quartz. In this study, the occurrence states of 13 impurity elements in quartz sand are systematically analyzed, including their modes of occurrence and distribution characteristics. Special attention is given to inclusion impurities, with detailed discussion of their types, interfacial structural features, and the fundamental mechanisms responsible for their resistance to removal. These insights provide a theoretical basis for understanding the limitations of existing purification processes. Furthermore, recent advances in three mainstream inclusion−breaking technologies—namely hydrofluoric acid etching, microwave−assisted acid leaching, and the combined process of roasting–water quenching–acid leaching—are comprehensively reviewed. The principles, effectiveness, and limitations of each method are comparatively evaluated. The analysis indicates that current technologies generally suffer from incomplete inclusion removal, a high dependence on hydrofluoric acid, and significant challenges associated with process coupling and optimization. In view of these limitations, future research should focus on the development of green, efficient, and controllable inclusion−fracturing technologies. Such advancements are essential for reducing reliance on high−quality mineral resources and ultimately achieving independent, secure, and sustainable production of high−purity quartz sand.