mineral

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Hardness: 7 on Mohs scale; Color: Purple, violet, to deep reddish-purple; Luster: Vitreous (glass-like); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Purple, violet, to deep reddish-purple
Luster: Vitreous (glass-like)

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins or cavities within hollow lavas (geodes). The purple color is caused by irradiation, iron impurities, and the presence of trace elements. Common in basaltic rocks and granite pegmatites.

Uses & applications

Primary use is in jewelry, lapidary arts (beads, cabochons), and decorative ornamental pieces. Historically used as an 'anti-intoxication' stone and as a gemstone for royalty.

Geological facts

Until the 18th century, amethyst was included in the cardinal gemstones (shared with diamond, sapphire, ruby, and emerald) before large deposits were found in Brazil. It is the birthstone for February.

Field identification & locations

Identification in the field is based on its hexagonal crystal habit, purple color that often concentrates at the tips, and its ability to scratch glass but not topaz. Major deposits are in Brazil, Uruguay, and Zambia.

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