sedimentary
Tumbled River Pebble (Quartzite / Agate)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale. Color: Brownish to tan. Luster: Vitreous to waxy. Structure: Microcrystalline/Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: ~2.65.
- Hardness
- 7 on Mohs scale
- Color
- Brownish to tan
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: Brownish to tan. Luster: Vitreous to waxy. Structure: Microcrystalline/Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: ~2.65.
Formation & geological history
Formed through natural water erosion and abrasive action in riverbeds or coastal environments, smoothing down hard silica-rich rock fragments over thousands to millions of years.
Uses & applications
Used primarily for landscaping, decorative stone displays, tumbling craft projects, or aquarium gravel.
Geological facts
Natural river pebbles undergo centuries of constant water currents and sediment friction, achieving a smooth, rounded finish naturally without artificial tumbling.
Field identification & locations
Identified by its smooth egg-like shape, lack of sharp edges, and high hardness (scratches glass). Commonly found along riverbanks, gravel pits, and beaches globally.
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