metamorphic
Quartzite (River Stone)
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Cream, tan, or yellowish-white; Luster: Vitreous to waxy; Structure: Non-foliated, granular; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Cream, tan, or yellowish-white
- Luster
- Vitreous to waxy
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Cream, tan, or yellowish-white; Luster: Vitreous to waxy; Structure: Non-foliated, granular; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed when quartz-rich sandstone is subjected to high heat and pressure during regional metamorphism, causing quartz grains to recrystallize and fuse together. The rounded shape indicates extensive water erosion.
Uses & applications
Used in construction for road ballast, flooring, and wall coverings. Smooth river-worn specimens are popular for landscaping, decoration, and home decor.
Geological facts
Quartzite is so durable that it can withstand millions of years of weathering and transport in river systems; it is harder and tougher than its parent sandstone.
Field identification & locations
Identify in the field by its inability to be scratched by steel and its lack of reaction to acid. Commonly found in riverbeds, glacial deposits, and mountain ranges.
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