metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, typically white to light grey or yellowish-brown due to iron oxide impurities, vitreous to greasy luster, non-foliated massive crystal structure, concoidal fracture, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically white to light grey or yellowish-brown due to iron oxide impurities, vitreous to greasy luster, non-foliated massive crystal structure, concoidal fracture, specific gravity around 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert through regional or contact metamorphism involving high heat and pressure, typically occurring over millions of years in mountain-building zones.
Uses & applications
Used in construction, road aggregate, railroad ballast, manufacturing of silica brick, decorative stone, and occasionally as a gemstone or countertop material.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why ridges formed of quartzite often persist as prominent mountain crests.
Field identification & locations
Identified in the field by its sugary texture, inability to be scratched by a steel knife, and lack of effervescence when tested with acid. Found worldwide in ancient orogenic belts.
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