metamorphic

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly with feldspar and mica impurities

AI-generated identification · may be incorrect

Gray-white, coarse crystalline texture with a dull to glassy luster and irregular fracture; individual grains appear fused. Hardness about 7 Mohs, no obvious cleavage, and specific gravity approximately 2.6–2.7.

Identified September 6, 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. Exact geological age cannot be determined from the photograph; quartzites occur in Precambrian through younger mountain belts.

Uses & applications

Used as crushed stone, road aggregate, building stone, landscaping material, and occasionally for countertops or decorative specimens. This rough piece has little gem value.

Geological facts

Quartzite is generally harder and more resistant to weathering than its sandstone precursor. The specimen may alternatively be a quartz-rich vein or silicified rock, which requires a fresh surface and testing for confident separation.

Field identification & locations

Look for fused quartz grains, a scratch on glass, and lack of reaction with dilute hydrochloric acid; sandstone shows visible grain boundaries and may crumble more readily. Common in metamorphic mountain regions worldwide.