metamorphic
Quartzite River Stone
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: light gray to off-white; Luster: dull to vitreous; Crystal structure: crystalline/granular; Cleavage: none; Specific Gravity: 2.63-2.65
- Hardness
- 7 on Mohs scale
- Color
- light gray to off-white
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: light gray to off-white; Luster: dull to vitreous; Crystal structure: crystalline/granular; Cleavage: none; Specific Gravity: 2.63-2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further shaped by fluvial (river) erosion, resulting in its smooth, egg-like ellipsoidal form.
Uses & applications
Used in landscaping, high-quality railroad ballast, as an abrasive in industrial processes, and occasionally as decorative garden stones.
Geological facts
Quartzite is so durable that it can outlast the mountains from which it came, often remaining as resilient boulders or pebbles long after the surrounding rock has weathered away.
Field identification & locations
Identify by its extreme hardness (it will scratch glass) and lack of reaction to acid. Commonly found in riverbeds, glacial deposits, and along coastlines where ancient metamorphic belts have eroded.
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