mineral
Quartz Cobble (River Stone)
Crystalline Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Milky white to yellowish-tan; Luster: Vitreous to waxy (when water-worn); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Milky white to yellowish-tan
- Luster
- Vitreous to waxy (when water-worn)
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Physical properties
Hardness: 7 on Mohs scale; Color: Milky white to yellowish-tan; Luster: Vitreous to waxy (when water-worn); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed from hydrothermal veins or within igneous cooling environments, later weathered out and smoothed by fluvial (river) or glacial transport over thousands of years.
Uses & applications
Used in landscaping, construction aggregate, and as a source for high-purity silica in industrial glass manufacturing.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. These rounded smooth shapes are the result of 'abrasion' during transport in water.
Field identification & locations
Identify by its ability to scratch glass and its lack of cleavage. Commonly found in riverbeds, beaches, and glacial till worldwide.
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