mineral
Amethyst
Quartz (SiO2) with iron impurities
Hardness: 7 (Mohs scale), Color: Purple to violet, Luster: Vitreous (glassy), Crystal structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Purple to violet, Luster: Vitreous (glassy), Crystal structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific gravity: 2.65
Formation & geological history
Formed in igneous or metamorphic environments, typically within hydrothermal veins or cavities (geodes) where silica-rich fluids crystallize. The purple color comes from irradiation of iron impurities.
Uses & applications
Primarily used as a gemstone in jewelry, as birthstone for February, and as a popular decorative specimen for collectors and holistic healing practitioners.
Geological facts
Until the 18th century, amethyst was considered one of the 'Cardinal gems' alongside diamond, ruby, sapphire, and emerald. Ancient Greeks believed it prevented intoxication.
Field identification & locations
Identify by its characteristic purple transparency and lack of cleavage. Common in Brazil, Uruguay, and Africa. Look for hexagonal crystal points and conchoidal fracture patterns.
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