sedimentary
Sandstone (Ferruginous)
Arenite with Iron Oxide matrix
Hardness (Mohs scale): 6-7; Color: Reddish-brown, tan, orange; Luster: Dull to earthy; Texture: Granular, sandpaper-like feel; Cleavage: None; Specific gravity: 2.2-2.8
- Color
- Reddish-brown, tan, orange
- Luster
- Dull to earthy
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Physical properties
Hardness (Mohs scale): 6-7; Color: Reddish-brown, tan, orange; Luster: Dull to earthy; Texture: Granular, sandpaper-like feel; Cleavage: None; Specific gravity: 2.2-2.8
Formation & geological history
Formed by the accumulation and lithification of sand-sized mineral particles or rock fragments in riverbeds, deserts, or coastal environments. The reddish tint suggests iron oxide (hematite or limonite) cementation.
Uses & applications
Commonly used as building stone, paving material, and in the production of glass (if high quartz content) and abrasive materials.
Geological facts
Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The variation in colors (like the red-brown seen here) is often due to the oxidation of iron minerals within the rock.
Field identification & locations
Identify in the field by its gritty texture and visible sand grains. This specimen appears flattened and water-worn, likely found in a river or stream bed as indicated by the background.
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