metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale. Color: White, grey, or yellowish. Luster: Vitreous to dull. Crystal structure: Hexagonal (microcrystalline). Cleavage: None, exhibits conchoidal fracture. Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- White, grey, or yellowish
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale. Color: White, grey, or yellowish. Luster: Vitreous to dull. Crystal structure: Hexagonal (microcrystalline). Cleavage: None, exhibits conchoidal fracture. Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure. This process causes the original quartz grains to recrystallize and fuse together into a dense, hard rock.
Uses & applications
Used as a decorative stone in architecture, as crushed stone for road construction, and as a raw material for the production of glass and silica-based products.
Geological facts
Quartzite is so hard that it can scratch steel. It is often more resistant to weathering than its parent sandstone, often forming ridges and hills in mountainous terrain.
Field identification & locations
Identify by its hardness (it will easily scratch glass) and its sugary, granular texture that looks like sand grains fused together. Look for it in metamorphic belts or as pebbles in stream beds.
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