mineral
Amethyst
Silicon Dioxide (SiO2) with Fe3+ impurities
Hardness: 7 on 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 Mohs scale
- Color
- Purple, violet, or lavender
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 on 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 of iron impurities in the quartz structure. Most specimens are from the Mesozoic or Cenozoic eras.
Uses & applications
Extensively used in jewelry (faceting, cabochons), ornamental carvings, and as a popular collectible for mineral enthusiasts.
Geological facts
Amethyst was considered a precious stone in ancient times, on par with diamonds. Its name comes from the Greek 'amethystos', meaning 'not intoxicated', as it was believed to prevent drunkenness.
Field identification & locations
Identify in the field by its distinct purple color, hexagonal crystal shape, and inability to be scratched by a steel blade. Common locations include Brazil, Uruguay, Zambia, and Ontario, Canada.
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Schist
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Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
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