mineral
Tumbled amethyst
Amethyst, purple variety of quartz (SiO₂)
AI-generated identification · may be incorrectPurple, translucent to opaque, with vitreous luster and trigonal crystal structure; Mohs hardness 7, no cleavage, and conchoidal fracture. The rounded surface appears mechanically tumbled and may conceal internal color zoning.
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Physical properties
Purple, translucent to opaque, with vitreous luster and trigonal crystal structure; Mohs hardness 7, no cleavage, and conchoidal fracture. The rounded surface appears mechanically tumbled and may conceal internal color zoning.
Formation & geological history
Amethyst forms when iron-bearing quartz crystallizes in silica-rich fluids, commonly lining volcanic-rock cavities; deposits span many geological ages, often hundreds of millions of years old.
Uses & applications
Used in jewelry, carvings, and mineral collections; tumbled stones are inexpensive decorative specimens.
Geological facts
Its purple color is associated with iron impurities and natural irradiation; heating can turn some amethyst yellow or orange.
Field identification & locations
Look for purple quartz with glassy luster and hardness sufficient to scratch glass; common sources include Brazil, Uruguay, and Zambia. The image supports identification as a small polished amethyst, but not its precise origin or treatment.
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