metamorphic
Weathered quartz-rich metamorphic rock (probable quartzite)
Quartzite, predominantly crystalline SiO₂, possibly derived from sandstone
AI-generated identification · may be incorrectHardness about 7 Mohs; pale tan to gray, with a granular texture and vitreous to dull luster. Massive, tightly interlocked quartz grains show no obvious cleavage; the dark fresh-cut face is consistent with quartz-rich rock, though the surface appears strongly weathered.
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Physical properties
Hardness about 7 Mohs; pale tan to gray, with a granular texture and vitreous to dull luster. Massive, tightly interlocked quartz grains show no obvious cleavage; the dark fresh-cut face is consistent with quartz-rich rock, though the surface appears strongly weathered.
Formation & geological history
Formed when quartz sandstone was recrystallized under heat and pressure during regional metamorphism; its precise geological age cannot be determined from the photograph. Weathering has produced the tan exterior and surface grooves.
Uses & applications
Used as crushed stone, road aggregate, building stone, landscaping rock, and occasionally decorative slabs. Attractive, sound pieces can have modest specimen or architectural value.
Geological facts
Quartzite commonly breaks across grains rather than around them and is generally more resistant to weathering than its sandstone precursor. The specimen could also be a weathered quartz-rich sandstone or gneiss; laboratory testing would confirm it.
Field identification & locations
Look for quartz grains that scratch glass, a sugary granular texture, and failure to fizz with dilute hydrochloric acid. Common in metamorphic mountain belts worldwide; likely hand-sized commercial or field-collected material.
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