sedimentary
Red Sandstone
Ferruginous Sandstone (SiO2 with Iron Oxide impurities)
Hardness: 6.5-7 (Mohs scale); Color: Red, orange, or reddish-brown; Luster: Dull to earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8.
- Hardness
- 6
- Color
- Red, orange, or reddish-brown
- Luster
- Dull to earthy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Red, orange, or reddish-brown; Luster: Dull to earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8.
Formation & geological history
Formed via the accumulation and cementation of sand-sized mineral particles or rock fragments. The red color is typically due to the presence of iron oxide (hematite) coating the grains, often in arid or desert environments over millions of years.
Uses & applications
Extensively used as a building material, paving stone, decorative architectural elements, and in the production of glass (if pure silica). It is also a popular specimen for educational geology kits.
Geological facts
Red sandstone is famous for creating the dramatic landscapes of the American Southwest, such as the Grand Canyon and Arches National Park. It has been used since ancient times for grand monuments, including the Petra treasury in Jordan.
Field identification & locations
Identify by its gritty, sandpaper-like texture and its tendency to rub off a bit of reddish dust. It often shows layering (bedding). Look for it in outcrops where ancient riverbeds or deserts once existed.
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