mineral
Amethyst Geode
Quartz (Silicon Dioxide, SiO2)
Hardness of 7 on the Mohs scale, pale to deep purple color due to iron irradiation, vitreous luster, trigonal crystal system, conchoidal fracture, specific gravity of 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, pale to deep purple color due to iron irradiation, vitreous luster, trigonal crystal system, conchoidal fracture, specific gravity of 2.65.
Formation & geological history
Formed in hollow cavities (vesicles) in volcanic rocks or altered limestones, where silica-rich hydrothermal solutions slowly deposit quartz crystals over millions of years.
Uses & applications
Used widely in jewelry, decorative ornamental carvings, spiritual and metaphysical practices, and as collector specimens.
Geological facts
The purple color in amethyst is caused by trace amounts of iron interacting with natural irradiation from the surrounding rock over geological time. Heating amethyst can turn it yellow or orange, creating citrine.
Field identification & locations
Easily identified by its distinctive purple crystalline druzy lining inside a hollow or nodular rock matrix. Found globally with major deposits in Brazil, Uruguay, Madagascar, and the United States.
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