mineral
Amethyst on Agate/Host Rock
Silicon Dioxide (SiO2) with iron impurities
Hardness: 7 (Mohs scale), Color: Purple to pale lavender, Luster: Vitreous (glassy), Crystal system: Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Purple to pale lavender, Luster: Vitreous (glassy), Crystal system: Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed in hydrothermal veins or volcanic geodes where silica-rich fluids crystallized over millions of years. The purple color comes from irradiation of iron impurities within the quartz structure. Typically Cretaceous or Tertiary in age.
Uses & applications
Primarily used in jewelry, as ornamental display specimens, and in metaphysical practices. Also a popular collector gemstone.
Geological facts
Amethyst was considered a 'Cardinal Gem' until large deposits were found in Brazil in the 1700s. Its name comes from the Greek 'amethystos', meaning 'not intoxicated', as it was believed to prevent drunkenness.
Field identification & locations
Identify in the field by its purple crystalline quartz structure often sitting atop a banded chalcedony (agate) or basalt base. Commonly found in Brazil, Uruguay, Zambia, and Arizona. Look for hexagonal terminations and color zoning.
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