mineral
Amethyst (Tumbled)
Silicon Dioxide (SiO2) with Fe3+ impurities
Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous when polished; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Purple, violet, or lavender
- Luster
- Vitreous when polished
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Physical properties
Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous when polished; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Forms in hydrothermal veins or volcanic geodes when silica-rich water precipitates in cavities. The purple color is caused by irradiation of trivalent iron (Fe3+) in the quartz structure.
Uses & applications
Primarily used for jewelry, lapidary arts, decorative items, and metaphysical collecting.
Geological facts
Amethyst was once considered one of the 'Cardinal Gems' along with diamond and ruby until large deposits were found in Brazil in the 1 plant9th century. Its name comes from the Greek 'amethystos', meaning 'not intoxicated'.
Field identification & locations
Identify by its characteristic purple color and quartz hardness. Common locations include Brazil, Uruguay, Zambia, and Ontario. Check for natural color zoning and internal inclusions to distinguish from glass or synthetic substitutes.
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