metamorphic
Quartzite
Quartzite (Metamorphosed Quartz Arenite)
AI-generated identification · may be incorrectHardness: 7 on the Mohs scale; Color: Pinkish-brown to white, reddish; Luster: Vitreous to greasy; Crystal structure: Trigonal (microcrystalline quartz grains); Cleavage: None (fractures conchoidally); Specific gravity: 2.65
- Hardness
- 7 on the Mohs scale
- Color
- Pinkish-brown to white, reddish
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale; Color: Pinkish-brown to white, reddish; Luster: Vitreous to greasy; Crystal structure: Trigonal (microcrystalline quartz grains); Cleavage: None (fractures conchoidally); Specific gravity: 2.65
Formation & geological history
Formed when quartz-rich sandstone or chert is subjected to high heat and pressure, typically through tectonic compression during orogeny. Geological age ranges from Precambrian to Cenozoic.
Uses & applications
Used in construction, as crushed stone for road bases, railway ballast, dimension stone, manufacturing of silica brick, and occasionally in decorative objects and countertops.
Geological facts
Pure quartzite is one of the most chemically inert and physically durable rocks on Earth, making it extremely resistant to weathering and erosion, often forming prominent mountain ridges.
Field identification & locations
Can be identified in the field by its sugary texture on fractured surfaces, extreme hardness (scratches glass), and the fact that quartz grains do not fizz with hydrochloric acid. Found worldwide in ancient mountain belts.
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