metamorphic

Likely quartzite

Quartzite, composed predominantly of quartz (SiO₂)

AI-generated identification · may be incorrect

The rough, tan-gray specimen has pale streaks and a dull to slightly glassy surface. Quartz has Mohs hardness 7 and trigonal crystal structure; grain size and cleavage are not clear in this image.

Identified September 29, 2026More metamorphic →

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Physical properties

The rough, tan-gray specimen has pale streaks and a dull to slightly glassy surface. Quartz has Mohs hardness 7 and trigonal crystal structure; grain size and cleavage are not clear in this image.

Formation & geological history

Quartzite forms when quartz-rich sandstone is recrystallized by heat and pressure during metamorphism. Its age and precise formation setting cannot be determined from the photograph.

Uses & applications

Used as crushed stone, building and decorative stone, and sometimes as a lapidary material.

Geological facts

Quartzite is typically much harder and more resistant to weathering than its sandstone precursor.

Field identification & locations

A likely quartzite; confirm by testing whether it scratches glass and whether grains remain fused rather than crumbling. Quartzite occurs in metamorphic belts worldwide; the specimen’s location is unknown.