sedimentary/metamorphic
River Pebble (Quartzite/Siltstone mixture)
Silicon Dioxide (SiO2) mixture with varied clastic minerals
Hardness: 6-7 (Mohs scale); Color: Tan/Brown/Beige; Luster: Dull/Waxy; Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.6-2.7
- Hardness
- 6-7 (Mohs scale)
- Color
- Tan/Brown/Beige
- Luster
- Dull/Waxy
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Tan/Brown/Beige; Luster: Dull/Waxy; Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the weathering and erosion of pre-existing rock masses, typically transported and rounded by water action in a river or stream bed over thousands of years.
Uses & applications
Commonly used in landscaping, road base, concrete aggregate, and as 'pocket stones' for casual collectors.
Geological facts
River rocks get their smooth, rounded shape through a process called 'saltation,' where stones are bounced along a riverbed, grinding off sharp edges.
Field identification & locations
Identify by its smooth, water-worn outer surface and uniform tan color. Found globally in alluvial deposits and ancient riverbeds.
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