mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 (Mohs), Color: Deep purple to pale 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), Color: Deep purple to pale violet, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed within igneous or volcanic rocks, typically in geodes or cavities where silica-rich fluids crystallize over time. Color is caused by iron impurities and natural irradiation during formation.
Uses & applications
Primarily used for jewelry, lapidary art, and as a popular collectable for mineral enthusiasts. Large geodes are used in interior decor.
Geological facts
Amethyst was considered a 'Cardinal Gem' and was as valuable as diamonds until the discovery of large deposits in Brazil in the 1700s. The name comes from the Ancient Greek 'amethystos', meaning 'not intoxicated'.
Field identification & locations
Identify by its purple color, Mohs hardness of 7, and lack of cleavage. Commonly found in Brazil, Uruguay, and across Africa. Look for hexagonal crystal points and conchoidal (curved) fracture surfaces.
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