arkosic arenite

Arkosic arenite, often simply called arkose, is a type of sandstone composed primarily of quartz and feldspar grains, with smaller amounts of mica. It is distinguished from other sandstones by its high feldspar content (over 25% of the sand grains) and lighter color compared to graywacke.1

The presence of arkose in the geological record can indicate specific environmental conditions. It suggests either an arid or glacial climate where feldspar weathers slowly, or a region with rapid uplift, erosion, and deposition where weathering processes are incomplete, allowing feldspar to be preserved. Arkosic sandstones are often reddish and can be interbedded with conglomerate, typically forming in alluvial fan or fluvial environments.12