sedimentary

Red Sandstone

Arenite (with Iron Oxide)

Hardness: 6-7 (Mohs scale); Color: Red, reddish-brown, tan; Luster: Dull, earthy; Crystal structure: Clastic (composed of sand-sized grains); Cleavage: None (fractures irregularly); Specific gravity: 2.2-2.8

Hardness: 6-7 (Mohs scale)
Color: Red, reddish-brown, tan
Luster: Dull, earthy

Identified April 2, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments (lithification). The red color indicates formation in an oxygen-rich environment where iron minerals oxidized. Commonly found in deserts, riverbeds, and ocean basins.

Uses & applications

Extensively used in construction for building blocks, flagstones, and paving. Highly valued as an architectural stone for historical buildings; crushed forms are used in road making.

Geological facts

Red sandstone is responsible for many of the Earth's most famous natural arches and canyons, such as those in the Grand Canyon and Petra in Jordan. The 'Old Red Sandstone' is a famous Devon-period formation in the North Atlantic region.

Field identification & locations

Identify by its gritty, sandpaper-like feel and visible grains. It is often found in layered beds or outcrops. Collectors should look for unique cross-bedding patterns or ripple marks preserved on the surface.