Kvartsisandstone

Kvartsisandstone is a clastic sedimentary rock formed from sand-sized quartz grains that have become lithified through diagenesis. Its defining feature is a predominance of quartz in the framework; most samples contain quartz as the principal mineral, with feldspar or lithic fragments present only as minor components. Quartz-rich varieties are commonly classified as quartz arenite, which is typically well sorted, well rounded, and cemented by silica; less pure forms may be arkosic or lithic quartz sandstone, where feldspar or rock fragments are more common.

Formation and diagenesis: Quartz sandstone forms from the deposition of quartz-rich sands in environments such as rivers, beaches, desert dunes, or shallow-marine settings. After burial, compaction and cementation lithify the sediment. Silica or carbonate cements often fill pore spaces, producing a hard, durable rock. The rocks can preserve well-developed sedimentary structures like cross-bedding and ripple marks in outcrops. Weathering and diagenetic processes can alter porosity and permeability, influencing groundwater flow and hydrocarbon storage.

Occurrence and uses: Kvartsisandstone is widespread in sedimentary basins around the world. It is valued as a building stone in some regions and serves as a source of silica for glassmaking and various industrial applications. The high quartz content generally makes the rock chemically inert and resistant to weathering.

Notable example: The Navajo Sandstone in the southwestern United States is a well-known exposure of a quartz-rich sandstone, famous for its extensive cross-bedding and dune-scale stratigraphy.

See also: quartz sandstone, sedimentary rocks, diagenesis.