metamorphic
Quartzite
Quartzite (SiO2 with minor impurities)
Mohs hardness of 7, vitreous to greasy luster, sugary/granular texture, translucent to opaque greyish-white with subtle greenish hues, no distinct cleavage.
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Physical properties
Mohs hardness of 7, vitreous to greasy luster, sugary/granular texture, translucent to opaque greyish-white with subtle greenish hues, no distinct cleavage.
Formation & geological history
Formed when quartz-rich sandstone undergoes intense heat and pressure during regional metamorphism, causing original quartz grains to recrystallize into an interlocking mosaic.
Uses & applications
Used as decorative stone, railway ballast, building material, floor tiles, and as a source of silica in glass and silicon production.
Geological facts
Unlike sandstone, quartzite breaks through its quartz grains rather than along the boundaries between them, creating a fracture surface that cuts across the original sand grains.
Field identification & locations
Identified by its extreme hardness (scratches glass easily), granular crystalline texture, and resistance to chemical weathering. Found worldwide in metamorphic rock terrains.
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