mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 (Mohs scale); Color: Pale violet to deep purple; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Pale violet to deep purple
- Luster
- Vitreous
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Physical properties
Hardness: 7 (Mohs scale); Color: Pale violet to deep purple; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65
Formation & geological history
Formed in hydrothermal veins and volcanic geodes. The purple color results from irradiation of trivalent iron (Fe3+) in the quartz structure. These can range from hundreds of millions to a few million years old.
Uses & applications
Primarily used as a gemstone in jewelry, for decorative carvings, and value by collectors for its aesthetic and 'metaphysical' appeal.
Geological facts
Amethyst was once considered one of the 'Cardinal gems' (precious along with diamond, ruby, sapphire, and emerald) until large deposits were found in Brazil in the 19th century.
Field identification & locations
Identify by its purple hue and ability to scratch glass but not topaz. Commonly found in Brazil, Uruguay, Zambia, and Canada. Look for hexagonal crystal points in geodes.
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