metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, color typically ranges from white to gray, pink, or yellowish-brown due to iron oxide impurities. It has a vitreous to greasy luster, a non-foliated massive crystal structure, lacks distinct cleavage, and has a specific gravity of 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, color typically ranges from white to gray, pink, or yellowish-brown due to iron oxide impurities. It has a vitreous to greasy luster, a non-foliated massive crystal structure, lacks distinct cleavage, and has a specific gravity of 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert through the process of regional or contact metamorphism, where intense heat and pressure fuse quartz grains together. Geologically, these rocks can span various ages from the Precambrian to the Cenozoic.
Uses & applications
Used widely in construction for road aggregate, railway ballast, building facades, decorative landscaping, and manufacturing of silica brick and glass.
Geological facts
Unlike sandstone which breaks around the grains, quartzite fractures directly through the quartz grains because of the extreme metamorphic welding. It is extremely resistant to weathering and erosion.
Field identification & locations
Can be identified in the field by its sugary texture on broken surfaces, high hardness that can easily scratch glass, and lack of effervescence with hydrochloric acid. Found worldwide in mountainous regions and ancient cratons.
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