gemstone
Tumbled amethyst
Amethyst, purple variety of quartz (SiO₂)
AI-generated identification · may be incorrectMohs hardness 7; purple, vitreous luster, trigonal crystal structure, and no true cleavage. The specimen is polished and rounded, so its natural crystal shape is not visible.
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Physical properties
Mohs hardness 7; purple, vitreous luster, trigonal crystal structure, and no true cleavage. The specimen is polished and rounded, so its natural crystal shape is not visible.
Formation & geological history
Amethyst forms when silica-rich fluids deposit quartz in cavities, commonly in volcanic rocks; its purple color comes from trace iron and natural irradiation. Deposits range from ancient to geologically recent.
Uses & applications
Used in jewelry, ornaments, and mineral collections; most tumbled pieces are decorative rather than gem-cut quality.
Geological facts
Amethyst is a variety of quartz, not a separate mineral species; its color can fade with prolonged strong sunlight.
Field identification & locations
Purple color and quartz-like translucence suggest amethyst, but confirmation may require testing because other purple minerals can resemble it. Common sources include Brazil, Uruguay, and Zambia.
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