sedimentary

Red Sandstone

Arenite (composed primarily of Quartz and Iron Oxide)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (based on quartz content); Color: Red, reddish-brown, or orange due to hematite; Luster: Dull/Earthy; Crystal structure: Clastic (grainy); Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6
Color: Red, reddish-brown, or orange due to hematite
Luster: Dull/Earthy

Identified June 26, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (based on quartz content); Color: Red, reddish-brown, or orange due to hematite; Luster: Dull/Earthy; Crystal structure: Clastic (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 suggests deposition in an oxygen-rich environment (arid or terrestrial) where iron minerals oxidized. Common in Mesozoic and Paleozoic formations.

Uses & applications

Extensively used as a building material, decorative stone in masonry, paving, and occasionally for grindstones or filter media.

Geological facts

Famous structures built from red sandstone include the Red Fort in Delhi and the ancient city of Petra. The 'Old Red Sandstone' is a famous geological sequence in Britain that helped pioneers of geology understand Earth's history.

Field identification & locations

Identify by its gritty, sandpaper-like texture and its layering (bedding planes). Found globally in sedimentary basins. Collectors often look for examples with unique ripple marks or cross-bedding.