metamorphic
Quartzite
Metamorphic Quartzite
Hardness: 7 on the Mohs scale; Color: Ranges from white and gray to pink, red, or dark brown due to iron oxide impurities; Luster: Vitreous to greasy; Crystal structure: Non-foliated, interlocking quartz crystals; Cleavage: None (fractures conchoidally through grains rather than around them);…
- Hardness
- 7 on the Mohs scale
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale; Color: Ranges from white and gray to pink, red, or dark brown due to iron oxide impurities; Luster: Vitreous to greasy; Crystal structure: Non-foliated, interlocking quartz crystals; Cleavage: None (fractures conchoidally through grains rather than around them); Specific gravity: 2.65 - 2.70.
Formation & geological history
Formed from quartz-rich sandstone or chert that has been subjected to extreme heat and pressure through regional or contact metamorphism, typically occurring during mountain-building events over millions of years.
Uses & applications
Used in construction, as crushed stone for roadbeds, in railway ballast, for manufacturing roofing tiles, and occasionally polished for decorative items or countertops.
Geological facts
Because quartz is extremely resistant to weathering, quartzite hills and ridges often stand out as prominent resistant landmarks in the landscape compared to surrounding softer rocks.
Field identification & locations
Can be identified in the field by its extreme hardness (it will easily scratch glass and cannot be scratched by a steel knife) and the characteristic sugary texture of fractured surfaces where quartz grains break across.
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