mineral

Amethyst quartz

Quartz, silicon dioxide (SiO₂), purple variety amethyst

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent purple and white, with vitreous luster and irregular/conchoidal fracture. It appears to be a rough, possibly partially polished quartz piece with druzy or fractured crystal surfaces; crystal structure is trigonal, and cleavage is absent or very poor.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms when iron-bearing silica-rich groundwater fills cavities in volcanic rocks, especially basaltic geodes; purple color develops through irradiation and heating. Most deposits formed in Mesozoic to Cenozoic volcanic environments, though age varies by locality.

Uses & applications

Used for jewelry, carvings, decorative specimens, and metaphysical collecting; large geodes are also ornamental. It is not typically used as a construction stone.

Geological facts

Amethyst is quartz colored mainly by trace iron and irradiation; heating can turn it yellow-orange, producing citrine. Purple intensity and natural crystal faces strongly affect desirability.

Field identification & locations

Identify it by purple quartz coloration, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; common sources include Brazil, Uruguay, Zambia, and Mexico. This specimen may also contain milky quartz or iron staining.