
sedimentary
Rounded quartz-rich pebble
Milky quartz or quartzite; predominantly silicon dioxide (SiO₂)
AI-generated identification · may be incorrectHardness about 7 Mohs; cream to pale tan, granular, and dull-to-waxy with possible sugary crystalline texture. Quartz has no cleavage, conchoidal fracture, and specific gravity near 2.65; the image is insufficient to distinguish quartz from quartzite confidently.
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Physical properties
Hardness about 7 Mohs; cream to pale tan, granular, and dull-to-waxy with possible sugary crystalline texture. Quartz has no cleavage, conchoidal fracture, and specific gravity near 2.65; the image is insufficient to distinguish quartz from quartzite confidently.
Formation & geological history
Likely a naturally weathered and water-rounded quartz pebble; if quartzite, it formed when quartz sandstone was metamorphosed and recrystallized. The specimen’s exact geological age and source cannot be determined visually.
Uses & applications
Common quartz pebbles have little commercial value, while quartzite is used as aggregate, landscaping stone, paving, and building material; attractive pieces may be collected or polished.
Geological facts
Quartz is one of Earth’s most abundant minerals and is chemically resistant, allowing it to survive transport as rounded beach- or river-pebbles.
Field identification & locations
Look for glassy fracture, lack of cleavage, and inability to scratch it with a steel knife; it should scratch ordinary glass. A vinegar test is generally uninformative, and a streak test is white.
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