mineral

Amethyst Geode

Quartz (SiO2)

Hardness: 7 on the Mohs scale. Color: Purple to violet. Luster: Vitreous (glassy). Crystal structure: Trigonal (hexagonal system). Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Purple to violet
Luster: Vitreous (glassy)

Identified August 3, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale. Color: Purple to violet. Luster: Vitreous (glassy). Crystal structure: Trigonal (hexagonal system). Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Formation & geological history

Formed in gas cavities in volcanic rocks (vesicles in basalt or other igneous rocks) where silica-rich hydrothermal fluids precipitate quartz crystals inward over millions of years.

Uses & applications

Used widely in jewelry, ornamental decorative items, crystal healing, and as a popular specimen for mineral collectors.

Geological facts

The purple color of amethyst is caused by irradiation, iron impurities, and the presence of other trace elements. Brazil and Uruguay are famous for producing massive amethyst geodes.

Field identification & locations

Readily identified by its distinctive purple crystal points lining a cavity, hexagonal crystal terminations, and a hardness of 7 which easily scratches glass. Commonly found in Brazil, Uruguay, Zambia, and the USA.