metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale. Color: White to grayish, often with pink or tan hues. Luster: Vitreous to waxy. Structure: Non-foliated, granular. Specific gravity: 2.6-2.7. Cleavage: Indistinct.
- Hardness
- 7 on Mohs scale
- Color
- White to grayish, often with pink or tan hues
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: White to grayish, often with pink or tan hues. Luster: Vitreous to waxy. Structure: Non-foliated, granular. Specific gravity: 2.6-2.7. Cleavage: Indistinct.
Formation & geological history
Formed when quartz-rich sandstone is subjected to high heat and pressure, causing the original quartz grains to recrystallize and fuse together. Typically Precambrian or Paleozoic in age.
Uses & applications
Used in construction as crushed stone or dimension stone, in high-end countertops, as a source for silica in glassmaking, and as decorative river stones.
Geological facts
Quartzite is so tough that it often survives intense weathering and forms the caps of mountains and ridges. It is often confused with marble, but unlike marble, it will not fizz in acid and can scratch glass easily.
Field identification & locations
Identify in the field by its extreme hardness and grainy, sugary texture. Found globally in mountainous regions or as water-worn cobbles in riverbeds and beaches.
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