sedimentary
River Pebble
Siliceous rock fragment / Quartzite / Sandstone pebble
Hardness: 6-7 on Mohs scale; Color: Brownish-gray, weathered; Luster: Dull to vitreous; Structure: Microcrystalline to clastic; Cleavage: None (fractures conchoidally); Specific gravity: 2.6-2.7
- Hardness
- 6-7 on Mohs scale
- Color
- Brownish-gray, weathered
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Brownish-gray, weathered; Luster: Dull to vitreous; Structure: Microcrystalline to clastic; Cleavage: None (fractures conchoidally); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the mechanical weathering, erosion, and transport of parent rock materials (often quartz-rich sandstone or quartzite) along riverbeds and streams over thousands to millions of years.
Uses & applications
Used in landscaping, decorative garden stones, construction aggregate, and as a natural smoothing stone in various crafts.
Geological facts
The smooth, rounded shape of a river pebble is caused by water tumbling the rock over long distances, causing it to collide with other rocks and sand in a process called attrition.
Field identification & locations
Identified by its smooth, water-worn, rounded shape and lack of sharp edges. Commonly found in riverbeds, lake shores, and ancient alluvial deposits worldwide.
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