metamorphic
Quartzite
Quartzite (composed primarily of Quartz, SiO2)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Grayish-white with sugary texture; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with sugary texture
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-white with sugary texture; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the original quartz grains to recrystallize and fuse together into a dense, hard rock.
Uses & applications
Used as a decorative stone in construction, as railway ballast, as a source of silica for glass making, and as a durable material for countertops.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, often forming the caps of hills and ridges. It is harder than a steel knife and will easily scratch glass.
Field identification & locations
Identify in the field by its extreme hardness and 'sugary' appearance of recrystallized quartz grains. It will not fizz with acid (unlike marble). Commonly found in folded mountain ranges.
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