sedimentary
River Pebble (Quartz/Sandstone)
Silicon Dioxide (SiO2) Mix
Hardness: 6-7 Mohs; Color: Tan, beige, or light brown; Luster: Dull to sub-vitreous; Structure: Microcrystalline or granular; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 Mohs
- Color
- Tan, beige, or light brown
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6-7 Mohs; Color: Tan, beige, or light brown; Luster: Dull to sub-vitreous; Structure: Microcrystalline or granular; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the mechanical weathering and water erosion of larger rock formations over thousands of years. Often starts as sandstone (sedimentary) or quartz veins.
Uses & applications
Landscape decoration, construction aggregate, aquarium gravel, and polished river stones for home decor.
Geological facts
The smooth, rounded shape is a direct result of 'abrasion'—the process of rocks tumbling against each other in a moving body of water like a river or stream.
Field identification & locations
Look for rounded, smooth edges and lack of distinct crystal faces. Commonly found in riverbeds, glacial deposits, and coastal beaches.
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