metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, yellow, or brown due to iron oxide impurities, vitreous to greasy luster, hexagonal crystal system when individual crystals are visible, conchoidal fracture, specific gravity of 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, yellow, or brown due to iron oxide impurities, vitreous to greasy luster, hexagonal crystal system when individual crystals are visible, conchoidal fracture, specific gravity of 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone or chert under high temperature and pressure conditions, typically in mountain-building belts or tectonic plate collisions.
Uses & applications
Used in construction, as crushed stone for roadbeds, in manufacturing railroad ballast, decorative aggregates, and occasionally for countertops and monument building.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why old sandstone ridges often weather into prominent quartzite ridges.
Field identification & locations
Identified by its inability to be scratched by a knife or glass, its granular sugary texture on fractured surfaces, and lack of effervescence with acid. Found worldwide in mountainous regions and ancient cratons.
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