metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, colors range from white and gray to pink and reddish-brown due to iron oxide impurities, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, indistinct cleavage, and a specific gravity of around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from white and gray to pink and reddish-brown due to iron oxide impurities, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, indistinct cleavage, and a specific gravity of around 2.65.
Formation & geological history
Formed when quartz-rich sandstone or chert is subjected to high heat and pressure, typically through tectonic compression in orogenic belts. Geological age can range from Precambrian to Cenozoic.
Uses & applications
Used in construction, as crushed stone for road bases, in manufacturing refractory bricks, and occasionally as an ornamental stone or in countertops.
Geological facts
Because quartz is extremely resistant to weathering, quartzite mountains often form the highest ridges and most resistant peaks in a landscape. It does not fizz when exposed to hydrochloric acid, unlike limestone.
Field identification & locations
Can be identified by its inability to be scratched by a steel knife, its sugary fracture surface showing interlocking crystals rather than breaking around sand grains, and common occurrence in mountainous regions or ancient beach deposits. Found worldwide.
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