mineral
Amethyst
Silicon dioxide (SiO2) with iron impurities
Hardness: 7 on Mohs scale; Color: Deep purple to pale lavender; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Deep purple to pale lavender
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 on Mohs scale; Color: Deep purple to pale lavender; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed in igneous or metamorphic environments, specifically within cavities or geodes of volcanic rocks like basalt. The purple color is caused by irradiation of trivalent iron (Fe3+) impurities within the quartz crystal lattice.
Uses & applications
Primarily used in jewelry (rings, necklaces, earrings), as decorative ornamental pieces, and as a popular specimen for mineral collectors. Also historically used for intaglio engraving.
Geological facts
The name comes from the ancient Greek 'amethystos', meaning 'not intoxicated', as it was believed to prevent drunkenness. It is the birthstone for February and was once considered as valuable as diamonds until large deposits were found in Brazil.
Field identification & locations
Identify by its characteristic purple color, hardness (will scratch glass), and lack of cleavage. Common locations include Brazil, Uruguay, Zambia, South Korea, and Ontario, Canada. Look for crystal habits in geodes or as tumbled stones at river outlets.
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