gemstone

Amethyst

Quartz, purple variety — silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent lavender-purple color, vitreous luster, trigonal crystal structure, and indistinct cleavage with conchoidal fracture. The specimen appears rough and possibly mounted as jewelry.

Identified August 19, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when iron-bearing silica-rich fluids fill cavities in volcanic rocks, especially basaltic lava flows; color develops through irradiation and heat-related effects. Most gem amethyst formed in relatively young-to-ancient volcanic cavities, commonly tens to hundreds of millions of years old.

Uses & applications

Used in jewelry, carvings, ornamental pieces, and mineral collections. Small rough mounted specimens have modest commercial value.

Geological facts

Purple color is caused primarily by iron impurities and irradiation; heating can turn some amethyst yellow, producing citrine. Amethyst is February’s birthstone.

Field identification & locations

Identify by purple translucent quartz, glassy luster, hardness sufficient to scratch ordinary glass, and lack of perfect cleavage; fluorite is softer and commonly shows more distinct cleavage. Major sources include Brazil, Uruguay, Zambia, and Namibia.