mineral

Amethyst quartz crystal cluster

Quartz, SiO₂; purple coloration from irradiation and trace iron

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, hexagonal crystal structure, no cleavage, conchoidal fracture, and specific gravity about 2.65. This specimen shows dark purple, translucent-to-opaque quartz with a pale druzy or matrix coating.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basaltic lava flows; crystal growth commonly occurred from the Paleozoic to Cenozoic eras. Common sources include Brazil, Uruguay, Zambia, and Mexico.

Uses & applications

Used as a decorative and lapidary material, in jewelry, carvings, geodes, and mineral collections; quartz also has major industrial uses in glass, electronics, and abrasives.

Geological facts

Amethyst is the purple variety of quartz and owes its color mainly to iron-related defects. Heating can change it to yellow citrine or produce ametrine in naturally zoned crystals.

Field identification & locations

Identify it by purple color, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; unlike fluorite, it does not cleave into cubes. Exact locality and crystal quality strongly affect value.