mineral

Amethyst Geode

Crystalline Quartz (SiO2) with iron impurities

Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Purple, violet, or lavender
Luster: Vitreous (glassy)

Identified June 26, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Gravity: 2.65

Formation & geological history

Formed in cavities (vesicles) of volcanic rock where silica-rich groundwater precipitates crystals over time. Most high-quality geodes are found in Brazil and Uruguay and date back to the Cretaceous period.

Uses & applications

Extensively used in jewelry (faceting, cabochons), home decor as statement pieces, and by collectors. Also popular in alternative healing and metaphysical practices.

Geological facts

The purple color comes from irradiation of trivalent iron (Fe3+) in the quartz structure. It was once considered as valuable as diamonds until large deposits were discovered in South America.

Field identification & locations

Identified by its characteristic purple crystals growing inward within a rocky outer shell or rind. Found commonly in Brazil, Uruguay, and Madagascar. Look for the 'geode' structure and hexagonal crystal points.

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