mineral

Tumbled amethyst

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; translucent violet-purple with a vitreous luster, no visible cleavage, conchoidal fracture, and trigonal crystal structure. The rounded surface indicates mechanical tumbling and polishing.

Identified September 6, 2026More mineral →

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Physical properties

Formation & geological history

Forms in cavities and geodes of volcanic rocks when silica-rich hydrothermal fluids deposit quartz; much material is Cretaceous to younger, though host-rock ages vary. Major sources include Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used for inexpensive jewelry, ornaments, polished stones, and mineral collecting. Commercial value depends on color, transparency, size, and natural versus treated origin.

Geological facts

Amethyst is the purple quartz variety and is February’s birthstone; heating can convert it to yellow citrine. The pictured specimen appears small, polished, and likely commercial grade.

Field identification & locations

Identify it by its purple color, glassy luster, hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common tumbled pieces are widely sold from Brazil and Uruguay.