mineral

Amethyst quartz cluster

Quartz, silicon dioxide (SiO₂), purple variety amethyst

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, hexagonal crystal structure, and no cleavage; purple coloration comes mainly from iron impurities and natural irradiation. This specimen shows purple terminated crystals on a white quartz/chalcedony-like matrix.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, especially basalt, where quartz crystals grow over long periods. Most deposits are Cenozoic to Mesozoic in age, depending on locality.

Uses & applications

Used for mineral collecting, carvings, cabochons, and jewelry; large clusters are popular decorative objects. It has modest commercial value unless crystals are exceptionally large, vivid, and undamaged.

Geological facts

Amethyst is quartz colored by trace iron-related defects; heating can convert it to yellow-orange citrine. Its purple color may fade with prolonged intense sunlight or heating.

Field identification & locations

Identify it by purple, glassy, six-sided quartz crystals and hardness sufficient to scratch ordinary glass; unlike fluorite, it lacks prominent cleavage. Common sources include Brazil, Uruguay, Zambia, Mexico, and the United States.