sedimentary

Red Sandstone

Arenite (Ferruginous Sandstone)

Hardness: 6-7 Mohs; Color: Brick red to brownish-red; Luster: Dull/Earthy; Crystal structure: Clastic (grainy); Cleavage: None; Specific gravity: 2.2-2.8

Hardness: 6-7 Mohs
Color: Brick red to brownish-red
Luster: Dull/Earthy

Identified July 5, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs; Color: Brick red to brownish-red; Luster: Dull/Earthy; Crystal structure: Clastic (grainy); Cleavage: None; Specific gravity: 2.2-2.8

Formation & geological history

Formed through the accumulation and lithification of sand-sized mineral grains or rock fragments, typically in desert or river environments. The red color suggests the presence of iron oxide (hematite) coating the grains, indicating formation in an oxygen-rich terrestrial environment.

Uses & applications

Used extensively in construction as dimension stone, paving, and decorative garden stone. Historically used for brownstone buildings. Fine-grained varieties are used for sharpening tools.

Geological facts

Red sandstones are often associated with 'Red Beds' in the geological record, which indicate periods of warm, arid climates. The Grand Canyon and many famous formations in the American Southwest are composed of thick layers of red sandstone.

Field identification & locations

Identified by its gritty sandpaper-like texture and its typical layered or bedded appearance. In the field, look for visible sand grains and the tendency to rub off slightly if scratched against a harder surface. Found globally, especially in areas with ancient sedimentary basins.