sedimentary

Sandstone

Arenite (primarily SiO2 with Fe2O3)

Hardness: 6-7 Mohs; Color: reddish-orange/terracotta; Luster: dull/earthy; Texture: granular, sandpaper-like feel; Structure: clastic; Cleavage: none.

Hardness: 6-7 Mohs
Color: reddish-orange/terracotta
Luster: dull/earthy

Identified June 23, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs; Color: reddish-orange/terracotta; Luster: dull/earthy; Texture: granular, sandpaper-like feel; Structure: clastic; Cleavage: none.

Formation & geological history

Formed via the accumulation and lithification of sand-sized mineral grains, primarily quartz and feldspar. The red hue indicates high iron oxide content from oxidative weathering during deposition.

Uses & applications

Commonly used as a building material, gravel, and in decorative landscaping. Highly valued in grindstones and as an aquifer material for groundwater storage.

Geological facts

The red color is due to the same process that causes rust; iron in the minerals reacts with oxygen. Red sandstone is famous for creating the iconic landscapes of the American Southwest, such as the Grand Canyon.

Field identification & locations

Identify by its gritty texture (feels like sandpaper) and visible sand grains. Found globally in basins and ancient deserts. Use a hand lens to see the rounded grains.