mineral

Amethyst crystal cluster

Quartz, purple variety (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; typically violet to purple, with vitreous luster, hexagonal crystal structure, and indistinct cleavage. The specimen shows intergrown, pointed quartz crystals with translucent edges and uneven fracture.

Identified August 25, 2026More mineral →

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Physical properties

Formation & geological history

Forms when iron-bearing quartz in volcanic cavities is irradiated and later heated or oxidized, commonly in basaltic geodes; most specimens formed during relatively young to ancient volcanic episodes, depending on locality.

Uses & applications

Used as a gemstone, jewelry and ornamental material, and mineral-collection specimen. Commercial value depends mainly on color saturation, crystal termination, transparency, and size.

Geological facts

Purple color results chiefly from irradiation-related defects involving iron impurities; heating can turn some amethyst yellow, producing citrine.

Field identification & locations

Identify by its purple color, glassy luster, hexagonal points, and hardness sufficient to scratch ordinary glass; unlike fluorite, it lacks prominent cleavage. Common sources include Brazil, Uruguay, Zambia, and Namibia.