sedimentary

Red Sandstone

Arenite (primarily Quartz with Hematite cement)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs); Color: Red, reddish-brown, or rust; Luster: Dull to earthy; Crystal Structure: Clastic texture (grainy); Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6-7 (Mohs)
Color: Red, reddish-brown, or rust
Luster: Dull to earthy

Identified April 6, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs); Color: Red, reddish-brown, or rust; Luster: Dull to earthy; Crystal Structure: Clastic texture (grainy); Cleavage: None; Specific Gravity: 2.2-2.8

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. The red color indicates formation in an oxygen-rich environment where iron minerals oxidized (rusted), common in desert or river-floodplain settings.

Uses & applications

Used extensively as a building material, decorative stone in landscaping, and as a source of high-purity silica in industrial glass-making. Historical monuments are often carved from durable varieties.

Geological facts

Many of the world's most famous natural landscapes, such as the Grand Canyon in the USA and Petra in Jordan, are composed of red sandstone. It is often referred to as 'Old Red Sandstone' when dating back to the Devonian period.

Field identification & locations

Identify in the field by its gritty, sandpaper-like feel and visible grains. It will not react with acid unless it contains calcite cement. Look for bedding planes or cross-bedding layers.