metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to grainy; Crystal structure: hexagonal (microcrystalline); Cleavage: none; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- white to light gray
- Luster
- vitreous to grainy
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to grainy; Crystal structure: hexagonal (microcrystalline); Cleavage: none; Specific gravity: 2.6-2.7
Formation & geological history
Formed when quartz-rich sandstone is subjected to intense heat and pressure during regional metamorphism, causing the quartz grains to recrystallize and fuse together.
Uses & applications
Used in construction as crushed stone for road ballast, as a dimension stone for flooring and countertops, and in the production of glass and silicon.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, frequently forming the peaks of ridges and mountain ranges.
Field identification & locations
Identified by its ability to scratch glass and its sugary, granular texture. Often found in mountainous regions or metamorphic belts worldwide.
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