sedimentary

Red Sandstone

Arenite (Ferruginous Sandstone)

Mohs hardness: 6 to 7; Color: reddish-brown to maroon; Luster: dull/earthy; Grain size: sand-sized (0.0625 to 2 mm); Texture: clastic and gritty to the touch; Composition: primarily quartz with iron oxide (hematite) cement.

Hardness: 6 to 7
Color: reddish-brown to maroon
Luster: dull/earthy

Identified July 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the accumulation and lithification of sand-sized mineral particles or rock fragments. The red color indicates formation in an oxygen-rich environment (subaerial) where iron minerals oxidize. These often date to the Permian or Triassic periods in many famous formations.

Uses & applications

Extensively used as a building material, decorative stone for paving, wall cladding, and in sculpture. In crushed form, it is used for road base and construction fill.

Geological facts

Red sandstone is famous for creating the iconic landscapes of the American Southwest, such as the Grand Canyon, Sedona, and Arches National Park. It is often referred to as 'Old Red Sandstone' in British geology.

Field identification & locations

Identified by its gritty sandpaper-like texture and its ability to scratch glass if quartz-rich. It is commonly found in desert basins, river deltas, and coastal environments. Check for visible layering or bedding planes.