mineral

Tumbled amethyst

Amethyst, purple variety of quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; translucent violet to lavender color, vitreous luster, trigonal crystal structure, and no true cleavage. The specimen appears polished/tumbled, with internal fractures or veils and uneven purple zoning.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms when iron-bearing quartz crystallizes in cavities of volcanic rocks, especially basaltic geodes; irradiation and natural heating produce the purple color. Major deposits are in Brazil, Uruguay, Zambia, and Bolivia, generally formed in Mesozoic to Cenozoic volcanic environments.

Uses & applications

Used for inexpensive jewelry, carvings, ornaments, geodes, and mineral collections; also marketed for decorative and spiritual purposes.

Geological facts

Amethyst is the traditional February birthstone and was historically valued alongside ruby, sapphire, and emerald. Prolonged heating can turn it yellow, producing citrine or ametrine-like material.

Field identification & locations

Identify it by purple quartz hardness, glassy luster, and absence of cleavage; glass is softer and commonly shows bubbles. Common localities include Brazilian and Uruguayan basalt geodes, with darker, transparent, evenly colored material generally more desirable.