mineral

Tumbled amethyst

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

AI-generated identification · may be incorrect

Mohs hardness 7; transparent to translucent purple with vitreous luster, conchoidal fracture, and no cleavage. Hexagonal quartz crystal structure is obscured by tumbling; the smooth surface is human-polished.

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Forms in cavities of volcanic rocks, especially basalt, when silica-rich hydrothermal fluids deposit quartz and amethyst over geologic time, commonly from the Mesozoic to Cenozoic. Major sources include Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used for inexpensive jewelry, carvings, ornaments, metaphysical displays, and mineral collections; it has limited industrial use compared with ordinary quartz.

Geological facts

Purple color varies from pale lilac to deep violet and can fade with prolonged heat or intense sunlight. Amethyst is February’s birthstone and a variety of quartz rather than a separate mineral species.

Field identification & locations

Identify by its purple color, glassy luster, hardness, and resistance to scratching by steel; polished pieces may show internal veils or banding. A tumbled form cannot reliably reveal its original host rock.