
mineral
Rounded quartz-rich pebble
Likely milky quartz or quartzite (SiO₂)
AI-generated identification · may be incorrectWhite to pale gray, opaque, smooth and water-worn with a vitreous-to-dull luster; quartz hardness is about 7 Mohs, with no cleavage and conchoidal fracture. The visible brown area may be iron-oxide staining or attached sediment.
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Physical properties
White to pale gray, opaque, smooth and water-worn with a vitreous-to-dull luster; quartz hardness is about 7 Mohs, with no cleavage and conchoidal fracture. The visible brown area may be iron-oxide staining or attached sediment.
Formation & geological history
Likely formed as a quartz vein fragment or quartzite clast, then rounded by stream or beach transport; its original geological age cannot be determined from the image. Commonly derived from weathering of igneous, metamorphic, or hydrothermal rocks.
Uses & applications
Primarily a decorative or teaching specimen; quartzite is also used as aggregate, roadstone, and building stone, while clear quartz may be used in electronics and jewelry.
Geological facts
Quartz is one of Earth’s most abundant minerals and is highly resistant to weathering, allowing it to persist as rounded pebbles. A glassy fracture and inability to scratch it with a steel knife support identification as quartz-rich material.
Field identification & locations
Common in stream gravels, beaches, glacial deposits, and quartz veins worldwide; test with a steel file or glass, inspect for granular texture, and distinguish from calcite by its greater hardness and lack of fizz in dilute acid.
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