mineral
Tumbled purple quartz, possibly amethyst
Quartz (SiO₂), likely iron-colored amethyst or purple chalcedony
AI-generated identification · may be incorrectHardness 7; translucent purple-gray color with a dull to vitreous luster and no obvious cleavage. The rounded, abraded surface indicates natural or human tumbling; crystal structure is trigonal quartz, though individual crystals are not visible.
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Physical properties
Hardness 7; translucent purple-gray color with a dull to vitreous luster and no obvious cleavage. The rounded, abraded surface indicates natural or human tumbling; crystal structure is trigonal quartz, though individual crystals are not visible.
Formation & geological history
Quartz formed from silica-rich hydrothermal fluids in cavities or veins, with trace iron producing purple coloration; the specimen was likely later weathered and tumbled. Exact geological age and locality cannot be determined from the image.
Uses & applications
Used as a lapidary and inexpensive jewelry/ornamental stone; quartz is also important in glass, electronics, and abrasives. This small specimen has modest collector value.
Geological facts
True amethyst usually shows clearer purple coloration and often visible crystal faces or zoning; opaque, mauve material may instead be purple chalcedony or dyed quartz.
Field identification & locations
Look for hardness sufficient to scratch glass, conchoidal fracture, and absence of strong cleavage; avoid destructive testing on valuable pieces. Common sources include Brazil, Uruguay, Zambia, and Madagascar.
