gemstone

Amethyst

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

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with vitreous luster, conchoidal fracture, and trigonal crystal structure. The specimen appears rough and naturally fractured, with pale lavender to deeper violet zoning.

Identified August 24, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in silica-rich volcanic cavities, especially within basaltic lava, where quartz-bearing fluids crystallize over long periods; commonly Cenozoic to older, depending on deposit. Major sources include Brazil, Uruguay, Zambia, and Mexico.

Uses & applications

Used as a gemstone, ornamental material, jewelry, crystal specimens, and occasionally in decorative polished pieces. Rough common material is widely available and primarily collectible rather than industrially important.

Geological facts

Amethyst is the purple variety of quartz and is the traditional birthstone for February. Heating can turn it yellow-orange, producing citrine or ametrine-like material.

Field identification & locations

Identify it by purple coloration, glassy luster, hardness sufficient to scratch ordinary glass, and absence of strong cleavage; purple fluorite is softer and commonly shows cubic cleavage. Look for cavity-grown crystals or banding in basalt and geodes.