metamorphic
Quartzite
Quartzite (SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale. Color: White to light grey with minor iron oxide staining (brownish specks). Luster: Glassy to sugary/vitreous. Crystal structure: Hexagonal/trigonal granular matrix. Cleavage: None (conchoidal to uneven fracture). Specific Gravity: 2.63 - 2.65.
- Hardness
- 7 on Mohs scale
- Luster
- Glassy to sugary/vitreous
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Physical properties
Hardness: 7 on Mohs scale. Color: White to light grey with minor iron oxide staining (brownish specks). Luster: Glassy to sugary/vitreous. Crystal structure: Hexagonal/trigonal granular matrix. Cleavage: None (conchoidal to uneven fracture). Specific Gravity: 2.63 - 2.65.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone, where high heat and pressure cause the quartz grains to recrystallize and fuse together solidly.
Uses & applications
Used as crushed stone in construction, railway ballast, decorative landscaping rock, and high-purity varieties are used to produce silicon metal and glass.
Geological facts
Unlike sandstone which breaks around individual sand grains, quartzite breaks directly through the quartz grains, producing a smooth or sugary fractured surface.
Field identification & locations
Identified by its extreme hardness (scratches glass easily) and sugary crystalline appearance without effervescing in acid. Commonly found in mountainous metamorphic terrains worldwide.
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