sedimentary

Red Sandstone

Arenite (with Iron Oxide cement)

Hardness: 6-7 (on Mohs scale); Color: Red, reddish-brown, or terracotta; Luster: Dull or earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific gravity: 2.2 - 2.8

Hardness: 6-7 (on Mohs scale)
Color: Red, reddish-brown, or terracotta
Luster: Dull or earthy

Identified March 20, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (on Mohs scale); Color: Red, reddish-brown, or terracotta; Luster: Dull or earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific gravity: 2.2 - 2.8

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral particles or rock fragments. The red color is typically the result of hematite (iron oxide) staining the grains during the lithification process, often in arid or continental environments like ancient deserts or riverbeds.

Uses & applications

Predominantly used as a construction material (building stone), paving material, decorative landscaping rock, and for architectural veneers. Historically used in the construction of temples, cathedrals, and monuments.

Geological facts

Red sandstone is famous for creating the iconic 'Red Rocks' of the American Southwest, such as those in Sedona, Arizona, and the Garden of the Gods in Colorado. Some formations, like the Old Red Sandstone, are over 400 million years old.

Field identification & locations

Identify by its gritty, sandpaper-like feel and uniform red coloration. In the field, look for visible layering (bedding planes). It is commonly found in sedimentary basins and arid regions globally. For collectors, look for specimens with unique cross-bedding or fossil inclusions.