metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, typically white, gray, pink, or reddish-brown due to iron oxide impurities. It has a vitreous to greasy luster, a non-foliated massive crystal structure, and breaks across quartz grains rather than around them.
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Physical properties
Hardness of 7 on the Mohs scale, typically white, gray, pink, or reddish-brown due to iron oxide impurities. It has a vitreous to greasy luster, a non-foliated massive crystal structure, and breaks across quartz grains rather than around them.
Formation & geological history
Formed from quartz-rich sandstone subjected to high heat and pressure, typically during tectonic mountain-building events (regional metamorphism).
Uses & applications
Used in construction, as crushed stone for road bases, in landscaping, for decorative wall tiles, and occasionally in countertops.
Geological facts
Because quartz is extremely resistant to weathering, quartzite ridges often form prominent resistant hills or mountains.
Field identification & locations
Can be identified in the field by its hardness (scratches glass easily), inability to be scratched by a knife, and the fact that it does not fizz with hydrochloric acid.
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