metamorphic
Quartz-rich metamorphic rock, likely quartzite
Quartzite; predominantly microcrystalline to granular SiO₂, possibly with mica and feldspar
AI-generated identification · may be incorrectHardness about 7 Mohs; white to gray with brown weathering and minor reddish staining, vitreous to dull luster, interlocking granular texture, and no obvious cleavage. The specimen appears strongly silicified and brecciated or veined.
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Physical properties
Hardness about 7 Mohs; white to gray with brown weathering and minor reddish staining, vitreous to dull luster, interlocking granular texture, and no obvious cleavage. The specimen appears strongly silicified and brecciated or veined.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism, commonly in Precambrian to younger mountain belts. The fractured appearance may reflect later tectonic deformation and mineralized veins.
Uses & applications
Used as crushed stone, road aggregate, building stone, and durable countertops; attractive pieces are collected or polished, though this specimen appears ordinary.
Geological facts
Quartzite is tougher and more resistant to weathering than its sandstone precursor. A likely identification can be tested by scratching glass and observing whether individual grains are fused rather than merely cemented.
Field identification & locations
Common in metamorphic terrains worldwide, including the Appalachian Mountains, Rocky Mountains, India, Brazil, and Scandinavia. A vinegar test is unhelpful; use a steel file or glass-scratch test, while noting that hard quartz veins can occur in other rocks.
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