sedimentary
Red Sandstone
Arenite (Ferruginous Sandstone)
Mohs hardness: 6 to 7; Color: brick-red, reddish-brown; Luster: dull/earthy; Crystal structure: clastic (sand-sized grains); Cleavage: none; Specific gravity: approx 2.0-2.6.
- Hardness
- 6 to 7
- Color
- brick-red, reddish-brown
- Luster
- dull/earthy
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Physical properties
Mohs hardness: 6 to 7; Color: brick-red, reddish-brown; Luster: dull/earthy; Crystal structure: clastic (sand-sized grains); Cleavage: none; Specific gravity: approx 2.0-2.6.
Formation & geological history
Formed by the accumulation and lithification of sand-sized silicate grains. The red color indicates the presence of iron oxide (hematite) deposited in terrestrial or shallow-marine environments during the compaction process.
Uses & applications
Commonly used in construction as a building material, for paving, decorative landscaping, and historical architecture. Finely ground sandstone is used in glass making.
Geological facts
Red sandstone is a primary component of many famous geological formations, such as the Red Rocks in Colorado and the 'Old Red Sandstone' seen across Great Britain.
Field identification & locations
Identify by its gritty, sand-like texture when rubbed. It can be found worldwide in riverbeds, deserts, and coastal cliffs. Red varieties are specific indicators of oxidizing environments.
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