metamorphic

Likely quartzite

Quartz-rich quartzite (predominantly SiO₂)

AI-generated identification · may be incorrect

Gray, fine- to medium-grained, granular surface with a subdued sheen; quartz has Mohs hardness 7, vitreous luster, and no cleavage. The photograph alone cannot confirm composition; a scratch test and fresh break would help distinguish it from other gray rocks.

Identified October 13, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when quartz-rich sandstone is recrystallized by heat and pressure, commonly during mountain building. Its age depends on the original sandstone and metamorphic event.

Uses & applications

Quartzite is used as building and paving stone, aggregate, and decorative stone; durable, attractive pieces may be collected or fashioned into ornaments.

Geological facts

True quartzite is very hard and typically breaks through quartz grains rather than around them, unlike many sandstones.

Field identification & locations

Look for a sugary, interlocking quartz texture and resistance to scratching by a steel knife; common in metamorphic mountain belts worldwide. The image shows a rounded gray specimen, but identification is tentative without testing.