mineral

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; purple to violet coloration, caused mainly by iron impurities and irradiation; vitreous luster, trigonal crystal structure, no cleavage, and conchoidal fracture. The specimen is polished/tumbled and contains visible internal fractures and color zoning.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Forms when quartz crystallizes in gas cavities and fractures of volcanic rocks, especially basalt, with iron-bearing fluids; many commercial specimens formed during the Mesozoic in Brazilian and Uruguayan lava flows. Individual crystals may be millions to hundreds of millions of years old.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and metaphysical collecting; transparent crystals are faceted as gemstones. It has limited industrial use beyond ordinary quartz applications.

Geological facts

Amethyst is the purple variety of quartz and is February’s birthstone; prolonged sunlight or heat can fade or turn it yellow-brown.

Field identification & locations

Identify it by its glassy luster, hardness, conchoidal fracture, and purple zoning; common sources include Brazil, Uruguay, Zambia, and Morocco. A tumbled piece lacks the natural crystal points and geode context useful for locality identification.