sedimentary
River Pebble (Quartz-rich)
Silicon Dioxide (SiO2) with impurities
Hardness: 7 (Mohs); Color: Tan, beige, off-white; Luster: Dull to sub-vitreous; Structure: Microcrystalline/Massive; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 (Mohs)
- Color
- Tan, beige, off-white
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 7 (Mohs); Color: Tan, beige, off-white; Luster: Dull to sub-vitreous; Structure: Microcrystalline/Massive; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the weathering and erosion of larger rock masses, typically igneous or metamorphic. These rounded shapes are created by long-term transport in riverbeds or coastal environments where water action smooths the surface.
Uses & applications
Primarily used in construction as aggregate, landscaping, decorative garden stones, and occasionally for rock tumbling by hobbyists.
Geological facts
River pebbles are natural time capsules that can be millions of years old, often originating from mountain ranges hundreds of miles away from where they are eventually found.
Field identification & locations
Identify by its rounded, smooth texture and high hardness (will scratch glass). Commonly found in stream beds, beaches, and glacial deposits. Look for uniform color and lack of visible grains.
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