metamorphic
Quartzite
Quartzite (primarily SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Pinkish-red (likely due to iron oxide impurities); Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None (breaks with conchoidal or irregular fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Pinkish-red (likely due to iron oxide impurities)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Pinkish-red (likely due to iron oxide impurities); Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None (breaks with conchoidal or irregular fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz sandstone. High heat and pressure causes quartz grains to recrystallize and fuse together, often during mountain-building events. Ages vary from Precambrian to Cenozoic depending on location.
Uses & applications
Used as crushed stone for road construction and railway ballast. High-purity quartzite is used in the manufacture of glass and silicon. Polished varieties are used for countertops, floor tiles, and decorative garden stones.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks, remaining as ridges or hilltops. Its pink color is often caused by trace amounts of hematite. It is significantly harder and more durable than the sandstone it originated from.
Field identification & locations
Identify in the field by its sugary/granular texture and its ability to scratch glass easily. Unlike marble (which it can resemble), it will not fizz when exposed to acid. Commonly found in old mountain ranges and glacial deposits.
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