mineral

Tumbled amethyst

Quartz, SiO₂; purple coloration from trace iron and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; violet to purple color, vitreous luster, and fractured/translucent appearance. Quartz is trigonal, lacks cleavage, and has specific gravity about 2.65; this specimen is polished/tumbled and shows internal fractures or inclusions.

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Forms when iron-bearing quartz crystallizes in gas cavities of volcanic rocks, especially basalt, with later irradiation producing the purple color. Most amethyst is geologically young on human timescales, commonly associated with Mesozoic–Cenozoic volcanic provinces.

Uses & applications

Used for beads, cabochons, carvings, ornamental objects, and mineral collecting; gem-quality material is used in jewelry. Lower-grade pieces are sold as polished decorative stones.

Geological facts

Amethyst is the purple variety of quartz and is February’s birthstone. Heating can turn it yellow-orange, producing citrine-like material, while prolonged sunlight may fade its color.

Field identification & locations

Identify it by purple quartz hardness, glassy luster, and absence of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, Zambia, and Bolivia; this appears to be a commercial tumbled specimen.