mineral

Purple quartz crystal, likely amethyst

Quartz (SiO₂), purple variety amethyst

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with gray-white areas, vitreous luster, hexagonal crystal structure, and indistinct cleavage with conchoidal fracture. The rough fragment appears partially terminated or fractured, with possible iron-oxide inclusions causing the color.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Amethyst forms when iron-bearing silica-rich fluids fill cavities in volcanic rocks, especially basalt, and irradiation colors the iron impurities purple. Individual crystals commonly formed in Mesozoic to younger volcanic geodes, though the specimen’s exact age and locality cannot be determined from the image.

Uses & applications

Used as a gemstone, ornamental crystal, and collector specimen; lower-grade material is used for carvings, polished pieces, and geode displays.

Geological facts

Amethyst is quartz colored by trace iron and natural irradiation; heating can turn it yellow-orange, producing citrine. Its purple color may fade with prolonged intense sunlight or heat.

Field identification & locations

Identify by its purple quartz color, glassy luster, hardness, and lack of prominent cleavage; a scratch test should not be used on valuable specimens. Common sources include Brazil, Uruguay, Zambia, and Morocco.