metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, colors range from white and gray to pink, brown, and yellowish due to iron oxide impurities. It has a vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture, and specific gravity of 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from white and gray to pink, brown, and yellowish due to iron oxide impurities. It has a vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture, and specific gravity of 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 varies widely from Precambrian to Cenozoic.
Uses & applications
Used in construction, railroad ballast, crushed stone for road aggregates, decorative landscaping, and occasionally as a dimensional stone for countertops and tiles.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why quartz-rich parent rocks often form ridges and prominent landscape features as surrounding softer rocks erode away.
Field identification & locations
Can be identified in the field by its sugary texture on fractured surfaces and the fact that it will scratch glass easily while not reacting with hydrochloric acid. Found worldwide in mountainous regions and ancient cratons.
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