metamorphic

Quartzite

Quartzite (chiefly SiO2)

AI-generated identification · may be incorrect

Hardness 7 on Mohs scale; Color: typically white, gray, or tan; Luster: vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: approx. 2.65.

Color: typically white, gray, or tan
Luster: vitreous to dull

Identified July 8, 2026More metamorphic →

Explore Quartzite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness 7 on Mohs scale; Color: typically white, gray, or tan; Luster: vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: approx. 2.65.

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in orogenic belts. This specimen appears water-worn, suggesting a secondary transport phase in a river or beach environment.

Uses & applications

Used in construction as crushed stone for road ballast, as a decorative stone in architecture (flooring/countertops), and sometimes as a source of silica for glass manufacturing.

Geological facts

Quartzite is so tough that it often outlasts its parent rock during erosion, forming resistant ridges or mountaintops. It is harder than steel and will easily scratch glass.

Field identification & locations

Identify in the field by its sugary, granular texture and extreme hardness. It won't react with acid (unlike marble) and will scratch a pocket knife blade. Common globally in metamorphic terrains.