sedimentary
Sandstone (River Rock)
Arenite (SiO2 based sedimentary rock)
Hardness: 6-7 Mohs; Color: Gray, tan, or brownish; Luster: Dull/Earthy; Structure: Clastic; Cleavage: None; Specific Gravity: 2.2-2.8. Features a sandy texture composed of visible mineral grains.
- Hardness
- 6-7 Mohs
- Color
- Gray, tan, or brownish
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 Mohs; Color: Gray, tan, or brownish; Luster: Dull/Earthy; Structure: Clastic; Cleavage: None; Specific Gravity: 2.2-2.8. Features a sandy texture composed of visible mineral grains.
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. This specific specimen has been rounded and smoothed by water erosion in a high-energy environment like a river or beach.
Uses & applications
Commonly used in landscaping, as a building material (cut stone), or as an abrasive. Naturally rounded stones are often used for decorative rock gardens.
Geological facts
Sandstone makes up about 10-20% of all sedimentary rocks on Earth. Because it is porous, sandstone often acts as an important aquifer for groundwater storage.
Field identification & locations
Identify in the field by its gritty texture (feels like sandpaper) and visible layering (bedding). Found worldwide in old riverbeds, deserts, and coastal regions.
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