gemstone
Polished amethyst
Quartz, SiO₂; purple variety colored by trace iron and irradiation
AI-generated identification · may be incorrectMohs hardness 7; purple with translucent to opaque zones and a vitreous luster. Trigonal crystal structure; no true cleavage, with conchoidal fracture. The specimen is shaped and polished.
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Physical properties
Mohs hardness 7; purple with translucent to opaque zones and a vitreous luster. Trigonal crystal structure; no true cleavage, with conchoidal fracture. The specimen is shaped and polished.
Formation & geological history
Amethyst forms as silica-rich fluids crystallize in cavities, commonly in volcanic rocks; its color develops from iron impurities and natural radiation. Deposits range from ancient to geologically recent.
Uses & applications
Used in jewelry, ornaments, and mineral collections; this small polished piece is primarily decorative or a lapidary specimen.
Geological facts
Amethyst is quartz, not a separate mineral species. Its purple color can vary with iron content, irradiation, and heat.
Field identification & locations
Identify by its purple color, glassy luster, hardness, and lack of cleavage; common sources include Brazil, Uruguay, Zambia, and Uruguay. The image shows a small polished piece, so locality cannot be determined.
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