metamorphic
Weathered quartz-rich rock, likely quartzite or milky quartz
Quartzite; chiefly quartz (SiO₂), with minor iron-oxide staining and possible feldspar/clay impurities
AI-generated identification · may be incorrectOff-white to pale gray, weakly translucent in small areas, with a dull to glassy luster and granular texture; quartz hardness is about Mohs 7, with no obvious cleavage and irregular fracture. The rounded shape and surface pitting indicate substantial weathering or stream abrasion.
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Physical properties
Off-white to pale gray, weakly translucent in small areas, with a dull to glassy luster and granular texture; quartz hardness is about Mohs 7, with no obvious cleavage and irregular fracture. The rounded shape and surface pitting indicate substantial weathering or stream abrasion.
Formation & geological history
If quartzite, it formed when quartz-rich sandstone was recrystallized during metamorphism, commonly during mountain-building; its exact age cannot be determined visually. A less-altered milky-quartz cobble is also possible.
Uses & applications
Quartzite is used as aggregate, road stone, building stone, and occasionally decorative material; attractive pieces may be collected but this specimen appears ordinary.
Geological facts
Quartz-rich rocks resist weathering, leaving rounded, durable cobbles while softer minerals erode away. Iron oxides produce the orange-brown spots.
Field identification & locations
Look for interlocking quartz grains that scratch glass and resist a steel knife; vinegar should not fizz. Common in metamorphic belts and quartz-rich river gravels, but a thin-section or hardness test is needed for confident identification.
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