sedimentary
River Pebble (Gravel)
Rounded clastic sediment
Hardness: 6-7 (Mohes scale); Color: Muted grey and brown with white quartz veins; Luster: Dull to earthy; Crystal structure: Cryptocrystalline or microcrystalline; Cleavage: None/Conchoidal.
- Hardness
- 6-7 (Mohes scale)
- Color
- Muted grey and brown with white quartz veins
- Luster
- Dull to earthy
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Physical properties
Hardness: 6-7 (Mohes scale); Color: Muted grey and brown with white quartz veins; Luster: Dull to earthy; Crystal structure: Cryptocrystalline or microcrystalline; Cleavage: None/Conchoidal.
Formation & geological history
Formed through the mechanical weathering of larger rocks, followed by transport and rounding in a high-energy aquatic environment such as a riverbed or shoreline.
Uses & applications
Commonly used in construction as aggregate for concrete, in landscaping and decorative gardens, and for road surfacing.
Geological facts
River pebbles are geological archives that can travel hundreds of miles from their source, becoming more spherical as they collide with other stones in the water current.
Field identification & locations
Identify in the field by its smooth, rounded edges and lack of sharp corners. Found globally in alluvial deposits, beaches, and ancient riverbeds.
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