mineral
Amethyst
Quartz (SiO2)
Hardness: 7 on the Mohs scale, Color: Purple to violet, Luster: Vitreous (glassy), Crystal Structure: Trigonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 on the Mohs scale, Color: Purple to violet, Luster: Vitreous (glassy), Crystal Structure: Trigonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed in gas cavities (vesicles) in basaltic volcanic rocks, or in hydrothermal veins, where silica-rich solutions deposit quartz crystals at low to moderate temperatures.
Uses & applications
Widely used as a gemstone in jewelry, decorative items, and by collectors. Also historically valued as an amulet.
Geological facts
The purple color is caused by irradiation, iron impurities, and the presence of trace elements. Amethyst was once considered one of the cardinal precious gemstones.
Field identification & locations
Easily identified by its distinct purple color and vitreous luster. Found worldwide, with notable deposits in Brazil, Uruguay, and parts of the USA (such as North Carolina).
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