Author name: Axel Müller

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.