Which mineral content defines Arkose sandstone?

• A. Quartz
• B. Calcite
• C. Mica
• D. Feldspar

Answer: (D)

Arkose sandstone is defined by a high feldspar content, making it feldspathic and compositionally immature. This abundance of feldspar signals relatively rapid erosion from feldspar-rich source rocks (often granitic terrains) with limited transport and chemical weathering, so the grains haven’t been worn down as much as in more mature sands. The grains are frequently angular, reflecting short transport distances. While quartz may be present, the defining trait is the substantial feldspar content, which sets arkose apart from quartz-rich sandstones (which are dominated by quartz) and from sands where calcite or mica are the standout minerals.