mineral

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Hardness: 7 on the Mohs scale; Color: light lilac to deep purple; Luster: vitreous; Crystal structure: Trigonal (hexagonal prisms); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 on the Mohs scale
Color: light lilac to deep purple
Luster: vitreous

Identified March 22, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale; Color: light lilac to deep purple; Luster: vitreous; Crystal structure: Trigonal (hexagonal prisms); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed in hydrothermal veins or as linings within volcanic rock (geodes). The purple color results from irradiation of trivalent iron (Fe3+) within the quartz structure. Age varies significantly depending on the host rock, from millions to billions of years.

Uses & applications

Primary use is in jewelry, lapidary arts, and gemstone collecting. Large amethyst geodes are popular decorative items. Historically believed to prevent intoxication.

Geological facts

Amethyst was once considered a 'Cardial Gem' alongside diamond, sapphire, ruby, and emerald until the discovery of large deposits in Brazil in the 18th century lowered its rarity.

Field identification & locations

Identify by its purple color, harness (cannot be scratched by a steel knife), and characteristic quartz crystal shape. Commonly found in Brazil, Uruguay, Zambia, and South Korea. Collectors should look for intense saturation of color and clarity.

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