mineral

Amethyst

Silicon dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Purple, violet, to deep reddish-purple; Luster: Vitreous (glass-like); Crystal structure: Hexagonal/Trigonal; 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 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins or geodes where silica-rich fluids deposit quartz. The purple color is caused by natural irradiation of trace iron impurities (Fe3+) in the crystal structure. Commonly found in basaltic rocks or volcanic cavities.

Uses & applications

Primarily used in jewelry (faceting and cabochons), decorative home decor, and as popular specimens for mineral collectors. Historically used in talismans and to prevent intoxication.

Geological facts

Amethyst is the birthstone for February. It was once considered one of the 'Cardinal Gems' and was worth as much as diamonds before large deposits were discovered in Brazil in the 1700s.

Field identification & locations

Identify in the field by its distinct purple color and 6-sided prismatic crystals. Commonly found in Brazil, Uruguay, Zambia, and South Korea. Look for conchoidal (shell-like) fractures rather than flat cleavage planes.