metamorphic
White quartz-rich river pebble, likely quartzite or milky quartz
Quartzite (mostly SiO₂); possibly massive milky quartz
AI-generated identification · may be incorrectWhite to cream, opaque, fine-grained to massive, with a dull-to-waxy luster and no obvious cleavage. Quartz hardness is Mohs 7; quartzite is typically dense (specific gravity about 2.6–2.7) and scratches glass, though the photograph alone cannot confirm the exact material.
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Physical properties
White to cream, opaque, fine-grained to massive, with a dull-to-waxy luster and no obvious cleavage. Quartz hardness is Mohs 7; quartzite is typically dense (specific gravity about 2.6–2.7) and scratches glass, though the photograph alone cannot confirm the exact material.
Formation & geological history
Quartzite forms when quartz-rich sandstone is metamorphosed under heat and pressure, commonly during mountain-building; its age depends on the source rock and may range from Precambrian to much younger. A massive quartz specimen would instead form from silica-rich hydrothermal fluids.
Uses & applications
Used as aggregate, road stone, building and decorative stone; attractive polished pieces are collected but usually have modest value.
Geological facts
The smooth shape indicates water or wave abrasion. Iron-oxide staining accounts for the faint tan spots and the specimen appears naturally weathered or tumbled.
Field identification & locations
Look for a sugary, interlocking quartz texture and inability to scratch it with a steel knife; quartzite should scratch glass. Common in stream beds, beaches, and glacial deposits worldwide.
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