metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale. Color: Tan, grey, or yellowish due to iron oxides. Luster: Vitreous to dull. Structure: Granular, non-foliated. Cleavage: None (breaks with conchoidal fracture). Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Tan, grey, or yellowish due to iron oxides
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale. Color: Tan, grey, or yellowish due to iron oxides. Luster: Vitreous to dull. Structure: Granular, non-foliated. Cleavage: None (breaks with conchoidal fracture). Specific Gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, causing the original quartz grains to recrystallize and fuse together.
Uses & applications
Used as crushed stone for road construction, railway ballast, and occasionally as decorative stone or flooring.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the ridges and peaks of mountain ranges because it weathers much slower than surrounding rocks.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sandpaper-like surface that does not rub off. It is commonly found in metamorphic mountain belts globally.
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