mineral

Amethyst Geode

Silicon Dioxide (SiO2) with iron impurities

AI-generated identification · may be incorrect

Hardness: 7 (Mohs), Color: Purple to violet crystals with white/gray agate banding, Luster: Vitreous (glassy), Structure: Hexagonal (trigonal), No cleavage, Conchoidal fracture

Identified July 20, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs), Color: Purple to violet crystals with white/gray agate banding, Luster: Vitreous (glassy), Structure: Hexagonal (trigonal), No cleavage, Conchoidal fracture

Formation & geological history

Formed in gas cavities (vesicles) within volcanic basalt or sedimentary limestone. Hydrothermal fluids rich in silica and traces of iron deposit crystals over thousands of years as the rock cools.

Uses & applications

Primarily used for interior decoration, crystal collecting, metaphysical purposes, and as a source for faceted gemstones in jewelry.

Geological facts

The purple color of amethyst comes from irradiation of trivalent iron impurities in the quartz structure. Geodes can range from tiny pebbles to 'cathedrals' several meters tall.

Field identification & locations

Look for heavy, rounded rocks that feel hollow when tapped. In the field, they often look like ordinary lumpy stones; once cracked open, they reveal the crystal interior. Major deposits are in Brazil and Uruguay.