mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 Mohs; Color: Pale violet to deep purple; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None; Specific gravity: 2.65
- Hardness
- 7 Mohs
- Color
- Pale violet to deep purple
- Luster
- Vitreous
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Physical properties
Hardness: 7 Mohs; Color: Pale violet to deep purple; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None; Specific gravity: 2.65
Formation & geological history
Formed in hydrothermal veins and basaltic geodes. Secondary crystallization occurs when silica-rich water fills rock cavities over millions of years, with color resulting from irradiation of iron impurities in the quartz structure.
Uses & applications
Extensively used in jewelry (faceting, cabochons), ornamental decoration, and as a popular mineral for metaphysical collections and interior design.
Geological facts
Amethyst was considered a precious stone equal to diamonds until large deposits were discovered in Brazil in the 1700s. Its name comes from the Greek 'amethystos', meaning 'not intoxicated'.
Field identification & locations
Identify by purple hue, 6-sided prismatic crystals, and lack of cleavage. Found in basalt cavities in Brazil and Uruguay; also found in Arizona and Ontario. Use a scratch test (harder than glass) to confirm as quartz.
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