metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-white with hints of green and tan; Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with hints of green and tan
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with hints of green and tan; Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under heat and pressure, causing the original quartz grains to recrystallize into an interlocking mosaic of crystals.
Uses & applications
Used in construction for road ballast, floor tiles, and countertop surfaces. Also used as a decorative stone and in the manufacturing of silica bricks.
Geological facts
Quartzite is so tough that it often survives weathering better than the rocks around it, creating prominent ridges or hills. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify in the field by its extreme hardness and its sugary, granular texture. Unlike marble, it will not react with acid. Commonly found in folded mountain belts globally.
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