metamorphic
Rounded quartz-rich pebble
Quartzite (probable), composed predominantly of quartz (SiO₂)
AI-generated identification · may be incorrectFine-grained, light gray to pinkish-gray, matte to sugary sparkle, with no obvious cleavage; quartz hardness is about Mohs 7 and specific gravity about 2.65. Its smoothly rounded shape indicates abrasion by water, ice, or sediment transport.
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Physical properties
Fine-grained, light gray to pinkish-gray, matte to sugary sparkle, with no obvious cleavage; quartz hardness is about Mohs 7 and specific gravity about 2.65. Its smoothly rounded shape indicates abrasion by water, ice, or sediment transport.
Formation & geological history
Likely formed when quartz-rich sandstone was recrystallized under metamorphic heat and pressure, commonly during mountain-building; exact geological age cannot be determined from the image. It was later weathered and rounded in a stream, beach, or glacial environment.
Uses & applications
Suitable as a durable decorative pebble, landscaping stone, aggregate, or small lapidary specimen; generally not jewelry grade without cutting and polishing. Common pieces have little commercial value.
Geological facts
The granular sparkle and resistance to scratching distinguish quartzite from softer sandstone. A steel file should not scratch it; however, visual identification alone cannot exclude granite, chert, or another quartz-rich rock.
Field identification & locations
Common in metamorphic terrains and transported widely by rivers and glaciers; notable sources include the Appalachian Mountains, Rocky Mountains, Scandinavia, and many river gravels. Confirm with a scratch test, streak, and close inspection for interlocking quartz grains.
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