mineral

Amethyst Geode

Silicon dioxide (SiO2) with iron impurities

Hardness: 7 on Mohs scale; Color: Pale lavender to deep violet; Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Pale lavender to deep violet
Luster: Vitreous (glassy)

Identified July 10, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Pale lavender to deep violet; Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in gas cavities (vesicles) in volcanic rock or sedimentary cavities. As mineral-rich water seeps into these cavities, amethyst crystals grow inward from the basaltic or agate shell. Most are Cretaceous to Jurassic in age.

Uses & applications

Highly valued as a gemstone in jewelry, used for ornamental decor, mineral collecting, and widely by practitioners of alternative medicine for its perceived calming properties.

Geological facts

The purple color of amethyst comes from irradiation, iron impurities, and the presence of trace elements. Exposure to high heat can turn amethyst yellow, producing citrine.

Field identification & locations

Identify by its purple macrocrystalline quartz structure inside a rocky or agate crust. Major commercial sources include Brazil (Rio Grande do Sul) and Uruguay. In the field, look for roundish nodules with a calcified exterior.

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