mineral

Amethyst (purple quartz)

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

AI-generated identification · may be incorrect

Mohs hardness 7; typically violet to lilac, with vitreous luster and translucent-to-transparent appearance. It has a hexagonal crystal structure and indistinct cleavage, breaking with conchoidal fracture; specific gravity is about 2.65.

Identified September 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basaltic lava, where quartz crystals grow in geodes. Most specimens formed during relatively young volcanic episodes, commonly from the Cenozoic to Mesozoic eras.

Uses & applications

Used as a gemstone, ornamental stone, mineral specimen, and in polished carvings; lower-grade material is used for décor and occasionally lapidary work.

Geological facts

Amethyst’s purple color can fade with prolonged heating or strong sunlight, and heating may produce yellow citrine. It is the February birthstone and historically was believed to prevent intoxication.

Field identification & locations

Identify it by its purple quartz color, glassy luster, hardness, and lack of prominent cleavage; it scratches glass but not easily with a steel knife. Major sources include Brazil, Uruguay, Zambia, Namibia, and Mexico.