mineral

Tumbled amethyst

Amethyst, purple quartz (SiO₂) colored mainly by iron-related defects

AI-generated identification · may be incorrect

Mohs hardness 7; purple to violet with translucent zones, vitreous luster, and no prominent cleavage. It has a trigonal crystal structure, though tumbling has rounded and polished the specimen; specific gravity is about 2.65.

Identified September 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids deposit quartz in volcanic cavities, commonly alongside iron minerals; coloration develops through irradiation and heating processes over geological time, typically in Phanerozoic volcanic rocks.

Uses & applications

Used as an inexpensive gemstone, ornamental stone, meditation/collecting material, and in polished cabochons, beads, and carvings.

Geological facts

Amethyst is the purple variety of quartz and is February’s birthstone. Heating can turn it yellow-orange, producing citrine or ametrine-like material.

Field identification & locations

Identify it by its glassy luster, hardness, quartz-like conchoidal fracture, and purple color, often with uneven zoning or milky inclusions. Major sources include Brazil, Uruguay, Zambia, and Bolivia; this example appears tumbled and polished.