mineral
Tumbled amethyst
Quartz, SiO₂; purple coloration from trace iron and irradiation
AI-generated identification · may be incorrectMohs hardness 7; translucent purple with vitreous luster and irregular internal fractures or inclusions. Trigonal crystal structure; no cleavage, with conchoidal fracture. The pictured piece is polished and rounded.
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Physical properties
Mohs hardness 7; translucent purple with vitreous luster and irregular internal fractures or inclusions. Trigonal crystal structure; no cleavage, with conchoidal fracture. The pictured piece is polished and rounded.
Formation & geological history
Amethyst forms as quartz crystals in gas cavities and fractures in volcanic rocks, often from silica-rich fluids. Deposits range from ancient to geologically recent; a specimen’s age cannot be determined from the image.
Uses & applications
Used in jewelry, ornaments, carvings, and mineral collections.
Geological facts
Amethyst is the purple variety of quartz; its color can fade with prolonged intense sunlight or heating.
Field identification & locations
Look for glassy luster, hardness sufficient to scratch glass, and purple color; common sources include Brazil, Uruguay, Zambia, and Madagascar. The photo shows a small polished specimen, but provenance and quality are unknown.
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