mineral
Tumbled amethyst
Amethyst, purple variety of quartz (SiO₂)
AI-generated identification · may be incorrectMohs hardness 7; purple with cloudy white inclusions, vitreous luster, and trigonal crystal structure. As a tumbled pebble, crystal faces and cleavage are absent; quartz has no cleavage and conchoidal fracture.
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Physical properties
Mohs hardness 7; purple with cloudy white inclusions, vitreous luster, and trigonal crystal structure. As a tumbled pebble, crystal faces and cleavage are absent; quartz has no cleavage and conchoidal fracture.
Formation & geological history
Forms when iron-bearing quartz crystallizes in silica-rich fluids, commonly lining volcanic-rock cavities; specimens range from relatively recent to hundreds of millions of years old.
Uses & applications
Used in jewelry, ornamental objects, and mineral collections; this small polished piece is mainly decorative.
Geological facts
Amethyst’s purple color is associated with trace iron and natural irradiation. Major sources include Brazil, Uruguay, Zambia, and Madagascar.
Field identification & locations
Look for purple color, glassy luster, and hardness sufficient to scratch glass; tumbling rounds edges and may obscure natural features. Exact locality cannot be determined from the image.
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