sedimentary

Sandstone

Arenite (SiO2 with Fe2O3)

Hardness: 6-7 (individual grains), Color: reddish-brown or rust-orange, Luster: dull/earthy, Texture: granular with visible quartz grains, Specific Gravity: 2.2-2.8

Identified March 31, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (individual grains), Color: reddish-brown or rust-orange, Luster: dull/earthy, Texture: granular with visible quartz grains, Specific Gravity: 2.2-2.8

Formation & geological history

Formed by the accumulation and cementation of sand-sized grains, typically quartz and feldspar, often in desert or river environments. Red color indicates oxygen-rich deposition where iron minerals oxidized.

Uses & applications

Extensively used in construction, paving, architecture (monuments), and glass manufacturing (if high silica). Smaller specimens are common for hobbyist collections.

Geological facts

Red sandstone is responsible for the dramatic landscapes of the American Southwest, such as the Grand Canyon and Zion National Park. It often preserves fossils and ripple marks from ancient environments.

Field identification & locations

Identified by its gritty feel (like sandpaper) and visible grains. Often found in layered beds or outcrops. Rubbing two pieces together will usually produce sand or dust.