mineral
Amethyst
SiO2 (Silicon Dioxide with Iron impurities)
Hardness: 7 on Mohs scale; Color: Pale lavender to deep purple; Luster: Vitreous (glass-like); Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Pale lavender to deep purple
- Luster
- Vitreous (glass-like)
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Physical properties
Hardness: 7 on Mohs scale; Color: Pale lavender to deep purple; Luster: Vitreous (glass-like); Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed in hydrothermal veins and basaltic geodes through the cooling of silica-rich water. Its purple color is a result of irradiation of iron impurities within the quartz lattice. Most specimens date back to the Cretaceous or Tertiary periods.
Uses & applications
Primarily used in jewelry (facet and cabochon cutting), interior decoration as geodes, and by collectors. Also historically used for making drinking vessels.
Geological facts
The name comes from the Greek 'amethystos', meaning 'not intoxicated', as it was believed to prevent drunkenness. It was once considered one of the five cardinal gemstones until large deposits were found in Brazil in the 19th century.
Field identification & locations
Identify by its purple zoning and hardness (it will scratch glass). Commonly found in Brazil, Uruguay, Zambia, and South Korea. Collectors look for deep saturation and clarity.
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