sedimentary
Sandstone (River Rock)
Arenite (SiO2 principal component)
Hardness: 6-7 Mohs; Color: Brown, tan, or grey; Luster: Dull to earthy; Texture: Granular and gritty; Cleavage: None; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 Mohs
- Color
- Brown, tan, or grey
- Luster
- Dull to earthy
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Physical properties
Hardness: 6-7 Mohs; Color: Brown, tan, or grey; Luster: Dull to earthy; Texture: Granular and gritty; Cleavage: None; Specific Gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments (clasts). This specific specimen shows river rounding, indicating transport by water in a fluvial environment over centuries.
Uses & applications
Common river stones are used in landscaping, as aggregate in construction, and for decorative masonry. Pure sandstone is used in glass manufacturing and as building stone.
Geological facts
Sandstone accounts for about 10-20% of the sedimentary rocks on Earth. The grit of sandstone is often used for sharpening tools, known as whetstones.
Field identification & locations
Identify by its gritty texture (feels like sandpaper) and visible sand grains. Found globally in riverbeds, canyons, and coastal areas. Collectors often look for examples with unique weathering or fossil inclusions.
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