mineral
Amethyst Geode Segment
Silicon Dioxide (SiO2) with trace Iron impurities
Hardness: 7 on Mohs scale; Color: Purple, violet; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); 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 (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed within volcanic gas bubbles (vesicles) or cavities in sedimentary rocks where hydrothermal fluids rich in silica and iron trace elements precipitate crystals over millions of years.
Uses & applications
Primarily used in jewelry, as decorative display specimens, and in metaphysical practices. High-quality clear crystals are often faceted.
Geological facts
The purple color is caused by irradiation of iron impurities within the quartz. It was once considered one of the 'Cardinal Gems' alongside diamond and ruby until large deposits were found in Brazil.
Field identification & locations
Identify by its distinctive purple crystalline habit inside a rocky host (matrix). Commonly found in Brazil, Uruguay, and Zambia. Collectors look for deep saturation of color and lack of inclusions.
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