metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale. Color: White to light gray or pale yellowish white. Luster: Vitreous to waxy. Crystal Structure: Trigonal/Hexagonal microcrystalline network. Cleavage: None (conchoidal or uneven fracture). Specific Gravity: 2.63 - 2.65.
- Hardness
- 7 on Mohs scale
- Color
- White to light gray or pale yellowish white
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: White to light gray or pale yellowish white. Luster: Vitreous to waxy. Crystal Structure: Trigonal/Hexagonal microcrystalline network. Cleavage: None (conchoidal or uneven fracture). Specific Gravity: 2.63 - 2.65.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone under high heat and intense pressure, causing individual quartz grains to recrystallize and interlock densely.
Uses & applications
Widely used as construction aggregate, railway ballast, dimension stone, decorative landscaping rock, and occasionally in glassmaking or as refractory bricks due to high silica purity.
Geological facts
Unlike sandstone which breaks around its constituent grains, quartzite breaks directly through the silica grains when fractured due to its extreme recrystallization and hardness.
Field identification & locations
Can be identified by its sugary texture, inability to be scratched by steel or glass, and clean sharp fracture surface. Very common in mountainous metamorphic terrains globally.
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