sedimentary
Sandstone (Greywacke/Siltstone variant)
Arenite / Wacke (SiO2 with diverse mineral inclusions)
Hardness: 6-7 (Mohs); Color: Grey, brown, tan; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; Cleavage: None; Specific gravity: 2.2–2.8
- Hardness
- 6-7 (Mohs)
- Color
- Grey, brown, tan
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (Mohs); Color: Grey, brown, tan; Luster: Dull/Earthy; Crystal structure: Granular/Clastic; 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 over millions of years, typically in marine, river, or desert environments.
Uses & applications
Commonly used as construction material, road aggregate, and in landscaping. Highly rounded specimens like this are often used as river stones for decorative or therapeutic tasks.
Geological facts
Sandstone contains about 20-25% of all sedimentary rock on Earth. It often preserves fossils and serves as a primary reservoir for groundwater and petroleum.
Field identification & locations
Identify by its gritty, sandpaper-like feel and visible grains. This specimen appears water-worn and rounded, likely sourced from a riverbed or coastal area. Common globally.
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