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; translucent violet color, vitreous luster, hexagonal crystal system, and indistinct cleavage with conchoidal fracture. The flat termination and purple zoning are consistent with a cut or naturally terminated quartz crystal.

Identified August 10, 2026More mineral →

Explore Amethyst (purple quartz) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Amethyst forms in silica-rich hydrothermal veins and volcanic cavities, commonly lining basalt vesicles; its host rocks range from Precambrian to Cenozoic. Major sources include Brazil, Uruguay, Zambia, Namibia, and Siberia.

Uses & applications

Used as a gemstone, ornamental crystal, geode material, and collector specimen; crushed quartz also has industrial uses, though gem-quality amethyst is primarily decorative.

Geological facts

Color intensity depends on iron content and radiation exposure; heating can turn some amethyst yellow or orange, producing citrine. Amethyst is February’s birthstone.

Field identification & locations

Identify it by purple color, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cubic cleavage; distinguish fluorite by amethyst’s greater hardness and quartz-like fracture. This small specimen is typically worth about $5–$25, or $25–$75 if unusually clear and well formed.