mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glass-like); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Purple, violet, or lavender
- Luster
- Vitreous (glass-like)
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Physical properties
Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glass-like); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Forms in hydrothermal veins and basaltic geodes through the precipitation of silica from aqueous solutions, colored by natural irradiation of trivalent iron (Fe3+). Often found in Cenozoic basalt cavities.
Uses & applications
Widely used in jewelry (faceting, cabochons), ornamental carvings, and as a popular specimen for mineral collectors and metaphysical practitioners.
Geological facts
The color of Amethyst can fade if exposed to prolonged sunlight. It was once considered a 'Cardinal Gem' and was as valuable as diamonds until large deposits were found in Brazil in the 19th century.
Field identification & locations
Identified by its purple hue and hexagonal crystal habits. Often found in Brazil, Uruguay, Zambia, and South Korea. Look for its transparency and typical crystal points in volcanic rock cavities.
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