sedimentary
River Pebble (Grey Quartzite / Sandstone Gravel)
Quartz-rich Sedimentary / Metamorphic River Pebble
Hardness: 6-7 on Mohs scale; Color: Light grey to dull bluish-grey with subtle earthy weathering stains; Luster: Dull to sub-vitreous; Texture: Fine-grained, smooth, water-worn, and rounded by fluvial erosion; Specific Gravity: Approx. 2.65.
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Light grey to dull bluish-grey with subtle earthy weathering stains; Luster: Dull to sub-vitreous; Texture: Fine-grained, smooth, water-worn, and rounded by fluvial erosion; Specific Gravity: Approx. 2.65.
Formation & geological history
Formed through fluvial (river/stream) transport and natural abrasion of silica-rich rocks like sandstone or meta-quartzite over thousands of years.
Uses & applications
Commonly used in landscaping, riverbed garden decoration, aquarium substrates, concrete aggregate, and casual rock painting.
Geological facts
Water-worn pebbles get their smooth, rounded shapes from continuous tumbling against other rocks in flowing river currents or ocean waves over long periods.
Field identification & locations
Found along riverbanks, lakeshores, beach coastlines, and glacial gravel deposits worldwide. Identified by its rounded, smooth surface and hard, silica-dominated composition.
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