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
Formed in hydrothermal veins or as linings within volcanic rock cavities (geodes). The purple color results from irradiation of trivalent iron (Fe3+) in the quartz structure. Most specimens range from late Mesozoic to Cenozoic eras.
Uses & applications
Primarily used as a gemstone in jewelry, decorative carvings, and as a popular collector's mineral. Occasionally used in industrial applications requiring high-purity quartz.
Geological facts
Amethyst was considered a 'Cardinal Gem' until the discovery of large deposits in Brazil in the 19th century. The name comes from the Greek 'amethystos,' meaning 'not intoxicated,' as Ancient Greeks believed it prevented drunkenness.
Field identification & locations
Identify in the field by its hexagonal crystal habit, purple hue, and inability to be scratched by a steel pocketknife. Common locations include Brazil, Uruguay, Zambia, and Ontario, Canada.
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sedimentary
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Metamorphic
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metamorphic
Gypsum (variety Selenite or Alabaster)
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Mineral
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Mineral/Rock
Granite
Granite (Phaneritic intrusive igneous rock)
igneous