mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 (Mohs scale); Color: Pale lilac to deep purple; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
- Hardness
- 7 (Mohs scale)
- Color
- Pale lilac to deep purple
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale lilac to deep purple; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
Formation & geological history
Formed in hydrothermal veins or volcanic geodes when silica-rich water cools. The purple color is caused by irradiation of iron impurities within the quartz structure. Typical age varies from millions to hundreds of millions of years.
Uses & applications
Primarily used as a gemstone in jewelry, for decorative carvings, and as a popular specimen for mineral collectors. It is also the birthstone for February.
Geological facts
Amethyst was as valuable as diamonds until large deposits were discovered in Brazil in the 19th century. The name comes from the Greek word 'amethystos', meaning 'not intoxicated', based on the ancient belief that it protected its owner from drunkenness.
Field identification & locations
Identified by its purple color and typical quartz-like crystal habits (hexagonal prisms). Small clusters like this are often sold as 'druze' or 'spirit quartz'. Common in Brazil, Uruguay, and Africa. Collectors should look for deep, uniform color and clarity.
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