metamorphic
Quartzite
Metamorphic Quartzite (SiO2-rich rock)
Hardness: 7 on Mohs scale. Color: Light grey to white with a sugary texture. Luster: Vitreous to greasy. Structure: Non-foliated, interlocking quartz grains. Specific Gravity: ~2.65.
- Hardness
- 7 on Mohs scale
- Color
- Light grey to white with a sugary texture
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale. Color: Light grey to white with a sugary texture. Luster: Vitreous to greasy. Structure: Non-foliated, interlocking quartz grains. Specific Gravity: ~2.65.
Formation & geological history
Formed through regional or thermal metamorphism of quartz-rich sandstone under intense heat and pressure, causing quartz grains to recrystallize into a dense network.
Uses & applications
Used extensively in construction as crushed stone, railway ballast, dimension stone for counter tops and tiles, and as a source of silica in glass manufacturing.
Geological facts
Unlike sandstone, when quartzite breaks, the fracture cuts through individual quartz grains rather than along the boundaries between them due to its tightly interlocking crystal matrix.
Field identification & locations
Identified by its high hardness (scratches glass easily) and sugary, sparky surface texture. Very common in mountainous metamorphic terrains around the world.
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