metamorphic
Quartzite
Metamorphic Quartzite
Hardness of 7 on the Mohs scale, color typically ranges from white and grey to pink or reddish-brown due to iron oxide impurities, vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, color typically ranges from white and grey to pink or reddish-brown due to iron oxide impurities, vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture, specific gravity around 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert through the processes of regional or contact metamorphism, where intense heat and pressure cause quartz grains to recrystallize and interlock.
Uses & applications
Used in construction, as crushed stone for roadbeds, railway ballast, building facades, decorative landscaping, and occasionally for countertops and ornamental carvings.
Geological facts
Quartzite is extremely durable and weather-resistant, which is why quartz-rich sandstones often transform into exceptionally tough mountain ridges as the surrounding softer rocks erode away.
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 fact that it breaks across the quartz grains rather than around them.
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