mineral
Amethyst
Quartz (Silicon Dioxide with Iron impurities), SiO2
Hardness: 7 (Mohs scale); Color: Purple, violet, or lavender; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Purple, violet, or lavender
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 (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
Forms in hydrothermal veins and basaltic geodes. The purple color is caused by irradiation, iron impurities, and the presence of trace elements. Found in rocks of various ages ranging from Precambrian to recent vulcanism.
Uses & applications
Used extensively in jewelry (faceted or cabochon), ornamental carvings, and as a popular mineral specimen for collectors.
Geological facts
Amethyst is the birthstone for February. Its name comes from the Ancient Greek 'amethystos', meaning 'not intoxicated', as it was believed to protect its owner from drunkenness.
Field identification & locations
Identify by its characteristic purple color and hexagonal crystal habits. Often found in geode cavities in volcanic rock. Common locations include Brazil, Uruguay, Zambia, and Ontario.
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