metamorphic

Quartzite

Quartzite (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale. Color: White to light grey with minor iron oxide staining (brownish specks). Luster: Glassy to sugary/vitreous. Crystal structure: Hexagonal/trigonal granular matrix. Cleavage: None (conchoidal to uneven fracture). Specific Gravity: 2.63 - 2.65.

Hardness: 7 on Mohs scale
Luster: Glassy to sugary/vitreous

Identified July 24, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed through the regional or contact metamorphism of quartz-rich sandstone, where high heat and pressure cause the quartz grains to recrystallize and fuse together solidly.

Uses & applications

Used as crushed stone in construction, railway ballast, decorative landscaping rock, and high-purity varieties are used to produce silicon metal and glass.

Geological facts

Unlike sandstone which breaks around individual sand grains, quartzite breaks directly through the quartz grains, producing a smooth or sugary fractured surface.

Field identification & locations

Identified by its extreme hardness (scratches glass easily) and sugary crystalline appearance without effervescing in acid. Commonly found in mountainous metamorphic terrains worldwide.