mineral

Amethyst fragment

Quartz, purple variety (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; translucent pale violet to purple, with a vitreous luster and conchoidal fracture. It has trigonal crystal structure and no true cleavage; the pictured piece appears cut or fractured and may be polished.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Amethyst forms when iron-bearing silica-rich fluids fill cavities in volcanic rocks, where irradiation and heat produce the purple color. Deposits commonly formed during the Mesozoic and younger, though age varies by locality.

Uses & applications

Used as a gemstone, ornamental stone, crystal specimen, and in polished décor; small fragments generally have modest value.

Geological facts

Purple color results mainly from irradiation-altered iron impurities. Heating can turn amethyst yellow-orange, producing citrine.

Field identification & locations

Identify by purple quartz color, glassy luster, hardness, and lack of cleavage; it should scratch ordinary glass but not be scratched by a steel blade. Common sources include Brazil, Uruguay, Zambia, and Mexico.