metamorphic
Rounded quartz-rich pebble, likely quartzite
Quartzite; predominantly crystalline SiO₂
AI-generated identification · may be incorrectTypically Mohs hardness 7, white to gray, vitreous to dull luster, granular interlocking quartz crystals, and no obvious cleavage; the pictured specimen appears water-worn and may have mica or weathering on its surface.
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Physical properties
Typically Mohs hardness 7, white to gray, vitreous to dull luster, granular interlocking quartz crystals, and no obvious cleavage; the pictured specimen appears water-worn and may have mica or weathering on its surface.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism, generally within ancient mountain belts; its exact age cannot be determined from the image.
Uses & applications
Used as durable aggregate, road stone, paving, and decorative stone; attractive pieces are collected, though this small pebble has minimal commercial value.
Geological facts
Quartzite is harder and more resistant to weathering than its sandstone precursor, commonly surviving as rounded stream or beach cobbles.
Field identification & locations
Look for a sugary crystalline texture, hardness sufficient to scratch glass, and fracture through quartz grains rather than around sand grains. Common in metamorphic terrains and transported into streams and glacial deposits.
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