metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-white with subtle banding; Luster: Vitreous to dull; Structure: Granoblastic, non-foliated; Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with subtle banding
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with subtle banding; Luster: Vitreous to dull; Structure: Granoblastic, non-foliated; Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under high heat and pressure, causing individual quartz grains to recrystallize into a dense, interlocking mosaic.
Uses & applications
Used as a decorative stone in landscaping, crushed for road construction ballast, and in the manufacturing of glass and ceramics due to high silica content.
Geological facts
Quartzite is so tough that it often survives intense weathering better than surrounding rocks, frequently forming the tops of ridges and hills.
Field identification & locations
Identify by its extreme hardness (can scratch glass) and its sugary texture that doesn't rub off. Often found in riverbeds as rounded cobbles due to its resistance to erosion.
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