mineral
Amethyst (Tumbled)
Amethyst (Silicon Dioxide with Iron impurities) - SiO2
Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Purple, violet, or lavender
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed in hydrothermal veins and cavities (geodes) of igneous rocks. It gets its purple color from irradiation of trivalent iron (Fe3+) in the quartz structure. Most specimens range from late Mesozoic to Cenozoic eras.
Uses & applications
Predominantly used in jewelry, lapidary arts, and as decorative collector specimens. Historically used for drinking vessels and talismans.
Geological facts
Amethyst is the birthstone for February. The name comes from the Greek 'amethystos', meaning 'not intoxicated', as it was once believed to prevent drunkenness.
Field identification & locations
Identify in the field by its characteristic purple color and hexagonal crystal termination. Commonly found in Brazil, Uruguay, and South Africa. This specific piece is 'tumbled,' meaning it has been mechanically polished to be smooth.
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