metamorphic

Quartzite

Quartzite (SiO2 with minor impurities)

AI-generated identification · may be incorrect

Mohs hardness of 7, vitreous to greasy luster, sugary/granular texture, translucent to opaque greyish-white with subtle greenish hues, no distinct cleavage.

Identified July 26, 2026More metamorphic →

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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.