mineral
Amethyst Geode
Amethyst/Purple Quartz (SiO2)
Hardness: 7 (Mohs scale), Color: light to deep purple, Luster: vitreous (glassy), Crystal structure: hexagonal/trigonal, Cleavage: none, Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: light to deep purple, Luster: vitreous (glassy), Crystal structure: hexagonal/trigonal, Cleavage: none, Specific Gravity: 2.65
Formation & geological history
Formed in volcanic or sedimentary rocks within cavities (gas bubbles), precipitated from silica-rich hydrothermal fluids over thousands of years. Common in basaltic cavities of the Cretaceous and Tertiary periods.
Uses & applications
Primarily used in jewelry (semiprecious gemstone), decorative home decor, and mineral collecting.
Geological facts
Amethyst was considered one of the five cardinal gemstones until the 18th century. The purple color is caused by irradiation and the presence of trace iron impurities.
Field identification & locations
Identify by purple hexagonal crystals pointing inward within a harder outer shell. Frequently found in Brazil and Uruguay. Collectors look for deep violet color and crystal clarity.
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