mineral

Amethyst Geode

Silicon Dioxide with impurities (SiO2)

Hardness: 7; Color: Purple to deep violet; Luster: Vitreous/glassy; Structure: Hexagonal (trigonal); Cleavage: None; Specific Gravity: 2.65

Hardness: 7
Color: Purple to deep violet
Luster: Vitreous/glassy

Identified May 1, 2026More mineral →

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Physical properties

Hardness: 7; Color: Purple to deep violet; Luster: Vitreous/glassy; Structure: Hexagonal (trigonal); Cleavage: None; Specific Gravity: 2.65

Formation & geological history

Formed in volcanic rock cavities (geodes) when silica-rich hydrothermal fluids precipitate over long periods. Usually found in basaltic rocks from the Mesozoic era.

Uses & applications

Used primarily in jewelry, as ornamental display specimens, in lapidary arts, and for gemstone collecting.

Geological facts

The purple color comes from irradiation of iron impurities within the quartz structure. It was once considered a Cardinal Gem along with diamond, ruby, emerald, and sapphire.

Field identification & locations

Identify by the crystal habit (six-sided prisms) and distinct purple hue. Commonly found in Brazil and Uruguay. Collectors look for deep saturation and lack of visible inclusions.