sedimentary
River Cobble (Quartzite / Sandstone)
Quartzite / Siliciclastic Sedimentary Rock
Hardness: 6-7 on Mohs scale. Color: Grayish-tan to brownish-pink weathered exterior. Luster: Dull, earthy to sub-vitreous. Texture: Smooth, rounded, water-worn cobble.
- Hardness
- 6-7 on Mohs scale
- Color
- Grayish-tan to brownish-pink weathered exterior
- Luster
- Dull, earthy to sub-vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Grayish-tan to brownish-pink weathered exterior. Luster: Dull, earthy to sub-vitreous. Texture: Smooth, rounded, water-worn cobble.
Formation & geological history
Formed through the accumulation and compaction of quartz-rich sand grains in riverine or beach environments, subsequently eroded and rounded by transport in stream beds or coastal waters.
Uses & applications
Commonly used in landscaping, river rock construction aggregate, decorative stone gardens, and general stone collecting.
Geological facts
Smooth cobbles like this are shaped over hundreds or thousands of years by the abrasive action of water and tumbling gravel in river channels.
Field identification & locations
Identified by its rounded cobble shape, smooth weathered surface, and high hardness (scratches steel). Found abundantly in riverbeds, glacial tills, and alluvial deposits worldwide.
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