gemstone

Amethyst

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

AI-generated identification · may be incorrect

Mohs hardness 7; transparent to translucent purple, with vitreous luster and conchoidal fracture. It is trigonal and lacks cleavage; the pictured piece appears tumbled or polished.

Identified August 21, 2026More gemstone →

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Physical properties

Mohs hardness 7; transparent to translucent purple, with vitreous luster and conchoidal fracture. It is trigonal and lacks cleavage; the pictured piece appears tumbled or polished.

Formation & geological history

Forms in cavities of volcanic rocks, especially basaltic lava flows, when silica-rich groundwater deposits quartz crystals over long periods. Most specimens formed during relatively young volcanic episodes, though exact age depends on locality.

Uses & applications

Used as an ornamental and jewelry gemstone, in carvings, geodes, and mineral collections. Common polished pieces are decorative rather than industrially significant.

Geological facts

Amethyst’s color ranges from pale lilac to deep violet and may fade with prolonged heat or sunlight. It is the February birthstone and a major variety of quartz.

Field identification & locations

Identify it by its purple color, glassy luster, hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, Zambia, and Bolivia.