sedimentary
Sandstone (River Pebble)
Quartz Arenite / Lithic Sandstone
Hardness: 6-7 on Mohs scale (due to dominant quartz grains). Color: Light greyish-green to tan with subtle reddish/brown iron oxide staining. Luster: Dull, earthy. Texture: Fine to medium-grained, sub-angular to well-rounded river cobblestone/pebble.
- Hardness
- 6-7 on Mohs scale (due to dominant quartz grains)
- Luster
- Dull, earthy
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Physical properties
Hardness: 6-7 on Mohs scale (due to dominant quartz grains). Color: Light greyish-green to tan with subtle reddish/brown iron oxide staining. Luster: Dull, earthy. Texture: Fine to medium-grained, sub-angular to well-rounded river cobblestone/pebble.
Formation & geological history
Formed through the accumulation, compaction, and cementation of sand-sized mineral grains or rock fragments (predominantly quartz and feldspar) in fluvial, lacustrine, or marine environments. Later eroded and smoothed by stream or river water transport.
Uses & applications
Commonly used as construction aggregate, landscaping stone, decorative garden rocks, and aquarium substrate. Fine-grained sandstones are also historically used for building dimension stone.
Geological facts
River-worn sandstone rocks often develop smooth, rounded shapes due to mechanical abrasion against other rocks and water currents over thousands to millions of years. The greenish-grey cast often comes from trace amounts of chlorite or reduced iron minerals.
Field identification & locations
Identify in the field by its granular, sandy texture visible under close inspection, uniform earthy color variations, and rounded cobble shape from erosion. Commonly found in riverbeds, glacial tills, beaches, and sedimentary rock outcrops worldwide.
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