mineral
Amethyst
Silicon dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Purple/violet; Luster: Vitreous/glassy; Crystal structure: Hexagonal; Cleavage: None; Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Purple/violet
- Luster
- Vitreous/glassy
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Physical properties
Hardness: 7 on Mohs scale; Color: Purple/violet; Luster: Vitreous/glassy; Crystal structure: Hexagonal; Cleavage: None; Specific gravity: 2.65
Formation & geological history
Forms in hydrothermal veins and geode cavities through the deposition of silica-rich water. Its purple color is caused by irradiation of iron impurities.
Uses & applications
Primarily used in jewelry, lapidary arts, gemstone collecting, and interior decoration.
Geological facts
Until the 18th century, amethyst was included in the cardinal gemstones, considered as valuable as diamonds and rubies until large deposits were found in Brazil.
Field identification & locations
Identify by its distinctive purple color and hexagonal crystal habit (if not tumbled). Its hardness is a key field test as it will scratch glass but not topaz. Found globally in Brazil, Uruguay, and South Korea.
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