metamorphic
Quartzite
Metamorphic quartz arenite
Hardness of 7 on the Mohs scale, typically white, gray, or yellowish due to iron oxide impurities, vitreous to greasy luster, massive to granular crystal structure, conchoidal fracture, and specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically white, gray, or yellowish due to iron oxide impurities, vitreous to greasy luster, massive to granular crystal structure, conchoidal fracture, and specific gravity around 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert under high temperature and pressure during regional or contact metamorphism, often over millions of years.
Uses & applications
Used in construction, as crushed stone for road building, in the manufacture of railway ballast, and occasionally as a decorative dimension stone or in countertops.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why ridges formed of quartzite often remain as prominent hills or mountain ranges after surrounding softer rocks have eroded away.
Field identification & locations
Can be identified in the field by its sugary texture and the fact that it breaks across the quartz grains rather than around them (unlike sandstone). Found worldwide in mountain-building belts.
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