Amethyst

Physical Properties

Hardness: 7 (Mohs scale), Color: Purple to violet, Luster: Vitreous/Glassy, Crystal structure: Trigonal/Hexagonal prism, Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Formation & Geological History

Formed in hydrothermal veins and cavities (geodes) of igneous rocks when silica-rich water cools. The purple color comes from irradiation of iron impurities in the quartz structure.

Uses & Applications

Primary use is in jewelry as a gemstone, decorative carvings, and as collectible specimens for mineral enthusiasts.

Geological Facts

Until the 18th century, amethyst was considered one of the most precious gemstones alongside diamond and ruby, until large deposits were found in Brazil. It is the birthstone for February.

Field Identification & Locations

Identify in the field by its distinct purple color and 6-sided crystal habit. Often found in Brazil, Uruguay, and Africa. Collectors should look for deep 'Siberian' purple hues for higher value.

Identified on: 4/28/2026

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