metamorphic

Quartzite

Metamorphic Quartzite (SiO2)

AI-generated identification · may be incorrect

Hardness of 7 on the Mohs scale, typically white, gray, or pinkish in color, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, conchoidal fracture, and specific gravity around 2.65.

Identified August 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed from quartz-rich sandstone subjected to high temperatures and pressures through regional or contact metamorphism, often taking millions of years in deep crustal environments.

Uses & applications

Used in construction, as crushed stone for roads, for railroad ballast, in manufacturing refractory bricks, and occasionally as decorative stone or in countertops.

Geological facts

Because quartz is extremely resistant to weathering, quartzite ridges often form prominent hills or mountain ranges as the surrounding softer rocks erode away.

Field identification & locations

Can be identified in the field by its extreme hardness (scratches glass easily), lack of reactivity with acid, and the way it breaks across the quartz grains rather than around them, unlike sandstone.