metamorphic

Quartzite

Quartz-rich metamorphic rock; chiefly SiO₂ (quartz)

AI-generated identification · may be incorrect

Typically white, gray, cream, or rusty from iron oxides, with a sugary granular texture and vitreous to dull luster. Hardness ~7 Mohs, no cleavage, conchoidal to uneven fracture, and specific gravity about 2.6; the specimen appears weathered and iron-stained.

Identified September 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when quartz-rich sandstone is recrystallized under substantial heat and pressure, commonly during regional mountain-building. Individual specimens may be Precambrian to much younger, depending on the source terrain.

Uses & applications

Used as crushed stone, aggregate, road material, building stone, countertops, and decorative slabs; attractive varieties are collected or polished.

Geological facts

Quartzite is generally harder and more resistant than its sandstone precursor. Iron-oxide staining can produce yellow, tan, orange, or reddish patches.

Field identification & locations

Identify it by its very high hardness: it scratches glass and typically breaks across quartz grains rather than around them; unlike sandstone, grains are tightly fused. Common in metamorphic mountain belts worldwide.