sedimentary
Sandstone Cobble
Arenite (Secondary classification based on grain size)
Hardness: 6-7 (Mohs scale); Color: Tan, brownish-yellow, buff; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None/Irregular fracture; Specific gravity: 2.1-2.8
- Hardness
- 6-7 (Mohs scale)
- Color
- Tan, brownish-yellow, buff
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Tan, brownish-yellow, buff; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None/Irregular fracture; Specific gravity: 2.1-2.8
Formation & geological history
Formed over millions of years from the accumulation of sand-sized mineral particles or rock fragments, cemented together by silica, calcium carbonate, or iron oxide. This specific piece shows significant rounding from water transport in a river or glacial environment.
Uses & applications
Used primarily in construction as a building material, road base, and as a source for glass-making silica if pure.
Geological facts
Sandstone represents about 20-25% of all sedimentary rocks on Earth. The rounded edges of this specific specimen suggest it was a river rock or 'cobble' transported long distances.
Field identification & locations
Identify by its sandy texture (gritty to the touch) and visible layering (bedding). Commonly found in dry river beds, canyons, and coastal bluffs.
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