mineral
Amethyst
Amethyst (Silicon Dioxide, SiO2 with Iron impurities)
Hardness: 7 (Mohs scale), Color: Pale lilac to deep purple, Luster: Vitreous (glassy), Crystal system: Hexagonal/Trigonal, Diaphaneity: Transparent to translucent, Specific gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Pale lilac to deep purple, Luster: Vitreous (glassy), Crystal system: Hexagonal/Trigonal, Diaphaneity: Transparent to translucent, Specific gravity: 2.65
Formation & geological history
Formed in hydrothermal veins or as linings within volcanic rock cavities (geodes). The purple color is caused by irradiation of iron impurities within the quartz crystal lattice.
Uses & applications
Primarily used in jewelry (as a semi-precious gemstone), lapidary art, and rock collecting. It is also the birthstone for February.
Geological facts
Amethyst was once considered as valuable as Diamond or Ruby until large deposits were found in Brazil in the 18th century. Ancient Greeks believed it could prevent intoxication.
Field identification & locations
Identify in the field by its distinct purple hue, lack of cleavage (conchoidal fracture), and ability to scratch glass. Commonly found in Brazil, Uruguay, Zambia, and Ontario.
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