gemstone

Amethyst

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

AI-generated identification · may be incorrect

Mohs hardness 7; purple to violet, vitreous luster, translucent to transparent, trigonal crystal structure, and indistinct cleavage with conchoidal fracture. The rounded, rough appearance suggests a tumbled or naturally water-worn specimen.

Identified September 6, 2026More gemstone →

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Physical properties

Formation & geological history

Forms primarily in silica-rich hydrothermal veins and cavities in volcanic rocks, especially basaltic geodes; crystals commonly developed during cooling from Paleozoic to Recent geological settings. Major sources include Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used as a gemstone, ornamental stone, mineral specimen, and in some quartz-related industrial applications. Value increases with strong saturated purple color, clarity, and attractive crystal form.

Geological facts

Amethyst is the February birthstone and one of the best-known quartz varieties. Heating can turn it yellow-orange, producing citrine or ametrine in suitable material.

Field identification & locations

Identify it by purple color, glassy luster, hardness sufficient to scratch ordinary glass, and white streak; unlike fluorite, it is harder and lacks prominent cleavage. Commonly found in volcanic geodes and hydrothermal cavities.