quartzrich

Quartzrich is a descriptive geological term used to characterize rocks or sediments that contain a very high proportion of quartz (SiO2). It is not a formal mineral species, but rather a relative descriptor applied in petrology and sedimentology to convey silica abundance. In siliciclastic settings, quartzrich rocks commonly refer to quartzarenites or quartz-rich sandstones, which typically have quartz making up the majority of the framework grains and show low contents of feldspar and lithic fragments. When such rocks undergo metamorphism, quartz-rich sandstone can transform into quartzite, a metamorphic rock composed largely of interlocking quartz grains.

Formation and provenance often explain quartz richness. High-maturity sediments experience extensive weathering, transport, and diagenesis, which remove unstable components and concentrate quartz grains. This process yields rocks with strong mechanical and chemical durability, light color, and well-sorted, rounded to subrounded quartz grains. Quartz-rich lithologies are typically associated with stable cratonic or arid to temperate tectonic settings where long transport and weathering have occurred.

Physical properties of quartz-rich rocks reflect their silica content. Quartz itself has a Mohs hardness of 7 and low chemical reactivity, contributing to the durability and high resistance to weathering of quartz-rich materials. In practical terms, quartz-rich sands are important as reservoir rocks in geology and as raw material for industrial uses such as glassmaking and ceramics, while quartzites are valued for their hardness and strength in construction contexts.

See also: quartzarenite, quartzite, siliceous rocks, sediment maturity.