mineral

Tumbled amethyst

Quartz, SiO₂; purple variety colored mainly by iron-related defects and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; transparent to translucent purple, with vitreous luster and no cleavage, showing conchoidal fracture. Amethyst is trigonal crystalline quartz, though tumbling has rounded and polished the specimen.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits quartz in cavities of volcanic rocks, commonly with iron impurities later modified by natural irradiation. Most commercial material formed in Mesozoic–Cenozoic volcanic environments, especially Brazil and Uruguay.

Uses & applications

Used as an ornamental stone, jewelry, carvings, beads, and mineral specimens. Small common tumbled pieces have modest decorative and collecting value.

Geological facts

Color ranges from lilac to deep violet and can fade with prolonged heat or strong sunlight. Amethyst is February’s birthstone and the traditional sixth wedding-anniversary gemstone.

Field identification & locations

Identify it by purple color, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; beware purple glass or dyed quartz. Major sources include Brazil, Uruguay, Zambia, Bolivia, and Mexico.