metamorphic
Quartzite River Stone
Metamorphic Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Greyish-white with tan/yellow iron staining; Luster: Dull to waxy; Texture: Granular but smooth due to river tumbling; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Greyish-white with tan/yellow iron staining
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Greyish-white with tan/yellow iron staining; Luster: Dull to waxy; Texture: Granular but smooth due to river tumbling; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed when quartz-rich sandstone is subjected to heat, pressure, and chemical activity of metamorphism, recrystallizing the grains. This specific specimen has been further shaped and polished by high-energy water transport in a river or coastal environment.
Uses & applications
Used as decorative landscaping stones, aquarium substrate, and occasionally crushed for high-silica industrial applications. Smooth specimens are often used in massage therapy (hot stones) or as prayer/worry stones.
Geological facts
Quartzite is one of the most durable and weather-resistant rocks on Earth. Because it is harder than steel, it often remains as high ridges or rounded river cobbles while surrounding softer rocks erode away.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its lack of reaction to acid (unlike marble). Common in floodplains, glacial till, and mountain stream beds.
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