metamorphic

Quartz-rich metamorphic rock, likely quartzite

Quartzite, composed predominantly of quartz (SiO₂), possibly with minor feldspar, mica, or iron oxides

AI-generated identification · may be incorrect

Hardness about 7 Mohs; gray-beige, massive, and granular with a dull to slightly glassy luster. Quartzite lacks obvious cleavage and commonly shows conchoidal or irregular fracture; the specimen appears weathered and water-worn.

Identified September 11, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone was recrystallized under heat and pressure during regional metamorphism, welding quartz grains together. Its exact geological age cannot be determined from the photograph; quartzites range from Precambrian to younger ages.

Uses & applications

Used as crushed stone, aggregate, building stone, paving, and decorative material; attractive varieties are collected or cut for cabochons and ornamental objects.

Geological facts

Quartzite is generally more resistant to weathering than its sandstone precursor and can form prominent ridges and durable stream cobbles.

Field identification & locations

A likely field test is scratching glass with little visible grain disintegration; dilute acid should not fizz unless carbonate minerals are present. Common worldwide in metamorphic belts and quartz-rich mountain terrains.