mineral
Tumbled amethyst
Quartz, purple variety; SiO₂
AI-generated identification · may be incorrectTypically purple to lilac with white quartz zoning, vitreous luster, and crystalline quartz structure; hardness 7 Mohs, no cleavage, conchoidal fracture, and specific gravity about 2.65. The rounded surface indicates tumbling and polishing.
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Physical properties
Typically purple to lilac with white quartz zoning, vitreous luster, and crystalline quartz structure; hardness 7 Mohs, no cleavage, conchoidal fracture, and specific gravity about 2.65. The rounded surface indicates tumbling and polishing.
Formation & geological history
Amethyst forms when iron-bearing quartz crystallizes in gas cavities and fractures of volcanic rocks, commonly basalt, followed by irradiation and heat-related color development. Most deposits formed during the Cenozoic or older volcanic episodes, depending on locality.
Uses & applications
Used as an ornamental gemstone, jewelry, carvings, mineral specimens, and metaphysical décor. Tumbled pieces are inexpensive collectibles.
Geological facts
Color intensity depends mainly on iron impurities and irradiation; heating can turn some amethyst yellow, producing citrine. Amethyst is February’s birthstone.
Field identification & locations
Identify it by purple quartz coloration, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; glass or fluorite may imitate it. Major sources include Brazil, Uruguay, Zambia, and Mexico.
