gemstone
Amethyst
Quartz (SiO2) - Amethyst variety
Hardness: 7 on the Mohs scale. Color ranges from light pinkish violet to a deep purple. Luster is vitreous (glass-like). Crystal structure is trigonal. Cleavage is none, and specific gravity is approximately 2.65.
- Hardness
- 7 on the Mohs scale
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Physical properties
Hardness: 7 on the Mohs scale. Color ranges from light pinkish violet to a deep purple. Luster is vitreous (glass-like). Crystal structure is trigonal. Cleavage is none, and specific gravity is approximately 2.65.
Formation & geological history
Formed within gas cavities (vesicles) in basaltic volcanic rocks, or as linings in hydrothermal veins, where silica-rich fluids deposit quartz crystals over millions of years.
Uses & applications
Widely used in jewelry, as a decorative gemstone, in lapidary arts, and prized by crystal collectors and practitioners.
Geological facts
Amethyst was historically considered one of the cardinal gemstones of high value until large deposits were discovered in Brazil. Its purple color is caused by irradiation and trace amounts of iron substituting for silicon within the quartz structure.
Field identification & locations
Identified by its distinctive purple coloration and quartz hardness (scratches glass, cannot be scratched by steel). Common sources include Brazil, Uruguay, Zambia, and the United States.
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