mineral

Amethyst

SiO2 (Silicon Dioxide) - Purple variety of Quartz

Hardness: 7 on the Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on the Mohs scale
Color: Purple, violet, or lavender
Luster: Vitreous (glassy)

Identified March 22, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in hydrothermal veins or inside volcanic geodes when silica-rich water cools. The purple color is caused by irradiation of trivalent iron (Fe3+) impurities. Formation can range from thousands to millions of years ago, often found in basaltic rocks.

Uses & applications

Primary use is in jewelry (faceted gemstones or cabochons) and as decorative specimens. It is also highly popular in the metaphysical and collecting communities as a February birthstone.

Geological facts

Amethyst was once considered one of the 'cardinal gems' and held equal value to diamonds until large deposits were discovered in Brazil in the 19th century. The name comes from the Greek word 'amethystos,' meaning 'not intoxicated.'

Field identification & locations

Identify in the field by its purple hue, hexagonal prism shape (if crystal faces are present), and its ability to scratch glass but not be scratched by a steel knife. Major deposits are in Brazil, Uruguay, and Zambia.

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