mineral
Tumbled amethyst
Quartz (SiO₂), purple variety known as amethyst
AI-generated identification · may be incorrectHardness 7 Mohs; translucent purple-and-white color with a vitreous luster and trigonal crystal structure. The rounded, glossy surface suggests it has been tumbled.
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Physical properties
Hardness 7 Mohs; translucent purple-and-white color with a vitreous luster and trigonal crystal structure. The rounded, glossy surface suggests it has been tumbled.
Formation & geological history
Amethyst forms when iron-bearing silica crystallizes in cavities, commonly in volcanic rocks; its purple color develops through trace iron and natural irradiation. Deposits range in age from ancient to geologically recent.
Uses & applications
Used for jewelry, ornaments, and mineral collections; it is also a popular inexpensive tumbled stone.
Geological facts
Amethyst’s color can fade with prolonged exposure to strong sunlight or heat. The photo supports a likely identification, but does not show enough detail for confirmation.
Field identification & locations
Look for purple quartz with a glassy luster and hardness sufficient to scratch glass; amethyst commonly occurs in geodes in Brazil and Uruguay, as well as elsewhere. The pictured stone appears small and polished.
