metamorphic
Weathered quartz-rich rock, possibly quartzite
Quartzite (mostly SiO₂), though the photograph is insufficient for confident identification
AI-generated identification · may be incorrectTan to golden-brown, opaque, massive and granular with a dull to vitreous luster; quartz hardness is about 7 Mohs, with no obvious cleavage and irregular fracture. Surface staining may reflect iron oxides or weathering.
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Physical properties
Tan to golden-brown, opaque, massive and granular with a dull to vitreous luster; quartz hardness is about 7 Mohs, with no obvious cleavage and irregular fracture. Surface staining may reflect iron oxides or weathering.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during metamorphism; ages vary widely from Precambrian to younger mountain-building events. The specimen may also be weathered quartz or a quartz-rich sedimentary rock.
Uses & applications
Quartzite is used as crushed stone, road aggregate, building and decorative stone, and occasionally as a lapidary material. This small rough specimen has mainly educational or collector value.
Geological facts
A useful field clue is that quartzite grains are fused, so a fresh surface generally scratches glass and breaks across grains rather than around them.
Field identification & locations
Common in metamorphic mountain belts worldwide, including the Appalachians, Rockies, Alps, and Scandinavian shield. Confirm with a glass-scratch test, close inspection of grain boundaries, and ideally acid and streak tests; image-based identification is uncertain.
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