Author name: Axel Müller

Humankind’s use of silica raw materials began at least 1.85 million years ago with production of flint tools and spans to today’s more than 1000 industrial applications, all relying on its chemistry and specific physical properties. Among the key achievements are the discovery of the piezoelectric effect of quartz for timekeeping, the critical importance of silicon-based semiconductor technologies for the digitalization of our society, and the production of renewable energy through photovoltaics. One of the greatest challenges regarding raw material supply and security lies in identifying new quartz deposits of sufficient purity, size, and properties to meet increasing demands. Although quartz is mined from a variety of deposits, economically viable sources remain difficult to locate for reasons that we explain.

Quartz and other silica minerals are amongst the most important constituents of the Earth’s crust, both as rock-forming mineral components and as tools for understanding Earth processes. Quartz and other forms of silica are essential parts of both the geological and biochemical cycles with the potential to help us understand the processes of our planet across disciplines. This article is a narrative of quartz, starting with its crystallization from fractionated, silica-rich magmas, transport, and deposition of silica by hydro- thermal fluids, as well as physical, chemical, and biogenic processes resulting in silica weathering, transport, accumulation, and the formation of sedimentary silica deposits. Extraterrestrial quartz and silica occurrences are also discussed.

Despite their simple chemical composition, silica (silicon dioxide, SiO₂) minerals comprise a complex system with diverse polymorphs of distinct crystal structures and different stabilities and properties. Quartz is arguably the most important mineral throughout human history, from early survival tools to critical materials for modern advanced technology. In addition, quartz and other silica polymorphs and varieties are excellent archivers and important tools for deciphering geological, environmental, and planetary processes and histories.