metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: White to light grey; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- White to light grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: White to light grey; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under extreme heat and pressure, typically during mountain-building events in various geological eras.
Uses & applications
Used as a decorative stone, in construction as crushed stone for roadbeds or railway ballast, and in the manufacture of glass and ceramics.
Geological facts
Quartzite is so durable that it can outlast the surrounding softer rocks in a landscape, often forming ridges or peak caps because of its resistance to weathering.
Field identification & locations
Identify by its hardness (it will scratch glass) and its sugary, granular texture. It does not react with acid like marble does. Commonly found in folded mountain belts globally.
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