metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness: 7 on the Mohs scale. Color: light gray to white with glassy texture. Luster: vitreous to greasy. Fracture: conchoidal or irregular. Cleavage: none.
- Hardness
- 7 on the Mohs scale
- Color
- light gray to white with glassy texture
- Luster
- vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale. Color: light gray to white with glassy texture. Luster: vitreous to greasy. Fracture: conchoidal or irregular. Cleavage: none.
Formation & geological history
Formed through the regional or contact metamorphism of quartz sandstone under high heat and intense pressure, recrystallizing quartz grains into a interlocking crystalline mosaic.
Uses & applications
Used widely in construction as crushed stone, ballast, and decorative landscaping stone. Also used as a raw material for glassmaking and silicon metal production.
Geological facts
Because quartzite consists almost entirely of quartz, it is extremely resistant to chemical weathering and erosion, often forming high ridges and hills in metamorphic terrains.
Field identification & locations
Identified in the field by its hardness (scratches glass), sugary to glassy texture, and the fact that fractures break through individual quartz grains rather than around them. Commonly found in riverbeds, glacial till, and mountainous metamorphic terrains.
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