metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale. Color: tan, yellow-brown, or white. Luster: vitreous to waxy. Structure: non-foliated, granular. Cleavage: none (fractures conchoidally).
- Hardness
- 7 on Mohs scale
- Color
- tan, yellow-brown, or white
- Luster
- vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: tan, yellow-brown, or white. Luster: vitreous to waxy. Structure: non-foliated, granular. Cleavage: none (fractures conchoidally).
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the original quartz sand grains to recrystallize and fuse together into a dense rock.
Uses & applications
Used as crushed stone for road construction, as cut slabs for countertops or flooring, and as a raw material in the glass or silicon industry.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of hills and ridges because it resists weathering better than surrounding rocks.
Field identification & locations
Look for a rock that can scratch glass easily and shows a crystalline, sugary texture on fresh surfaces. Unlike sandstone, quartzite fractures across the sand grains rather than around them.
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