sedimentary
Red Sandstone
Sandstone (principally Quartz with Iron Oxide coating)
Hardness: 6-7 (Mohs); Color: Reddish-brown/Terracotta; Luster: Dull/Earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8
- Hardness
- 6-7 (Mohs)
- Color
- Reddish-brown/Terracotta
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (Mohs); Color: Reddish-brown/Terracotta; Luster: Dull/Earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation of sand-sized mineral particles or rock fragments, cemented together by silica or calcium carbonate. The red color suggests deposition in an oxygen-rich environment (arid or continental) where iron minerals oxidized.
Uses & applications
Used widely in construction for building facades, paving, and decorative garden walls. Fine-grained varieties are used for whetstones and artistic carvings.
Geological facts
The famous red rock formations in Sedona, Arizona, and the Royal Concert Hall in Scotland are composed of this rock type. It is often a key indicator for ancient desert or river environments.
Field identification & locations
Identify in the field by its gritty texture (feels like sandpaper) and distinct layering. Common in arid basins and along coastal cliffs. Collectors look for unique banding or fossil impressions.
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