mineral

Amethyst

Silicon Dioxide with iron impurities (SiO2)

Hardness: 7 on the Mohs scale; Color: Pale lilac to deep royal purple; Luster: Vitreous (glass-like); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Pale lilac to deep royal purple
Luster: Vitreous (glass-like)

Identified March 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins or cavities within volcanic igneous rocks (geodes). The purple color results from irradiation of trivalent iron (Fe3+) in the quartz structure. Most commercial deposits date from the Cretaceous period.

Uses & applications

Primarily used in jewelry (faceting and cabochons), as decorative display specimens, and in spiritual/metaphysical practices.

Geological facts

Until the 18th century, amethyst was considered one of the 'cardinal gems' (alongside diamond, ruby, emerald, and sapphire) until large deposits were found in Brazil. It is the birthstone for February.

Field identification & locations

Identify in the field by its distinct purple hexagonal crystal points and its ability to scratch glass but not topaz. Commonly found in Brazil, Uruguay, Zambia, and Ontario, Canada.

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