sedimentary

Red Sandstone

Arenite (primarily Quartz SiO2 with Hematite Fe2O3 cement)

Hardness: 6-7 on Mohs scale; Color: Reddish-brown to pink due to iron oxide; Luster: Dull/Earthy; Crystal structure: Clastic (granular); Cleavage: None (breaks across grains); Specific Gravity: 2.0-2.6.

Hardness: 6-7 on Mohs scale
Color: Reddish-brown to pink due to iron oxide
Luster: Dull/Earthy

Identified March 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the accumulation of sand-sized mineral particles or rock fragments, usually in desert or river environments. The red color suggests deposition in an oxygen-rich environment (terrestrial) where iron minerals oxidized. Ages vary widely from Precambrian to Cenozoic.

Uses & applications

Commonly used as a building material, paving stone, and in landscaping. Historically used for monuments and carving. In the oil industry, it can serve as a reservoir rock due to its porosity.

Geological facts

Many famous landmarks, such as the Grand Canyon and the 'Red Rocks' of Sedona, Arizona, are primarily composed of red sandstone layers. It often preserves ripple marks and cross-bedding from ancient winds or water currents.

Field identification & locations

Identify in the field by its gritty 'sandpaper' feel and visible layers (bedding). Rubbing two pieces together usually produces sand grains. Found globally, with massive deposits in the Southwestern USA, Scotland, and Central Australia.

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