mineral

Amethyst cluster

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron-related defects

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, translucent to transparent purple crystals, and no true cleavage; quartz has a trigonal crystal structure and specific gravity about 2.65. The specimen appears naturally clustered, though strong colored lighting may affect its apparent hue.

Identified August 7, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basaltic geodes; coloration develops from trace iron and irradiation. Most gem-quality amethyst formed in Phanerozoic volcanic environments, commonly tens to hundreds of millions of years old.

Uses & applications

Used for cabochons, faceted gems, carvings, spiritual objects, and mineral collections; lower-grade material is used as decorative stone. Value depends heavily on color saturation, crystal form, clarity, and size.

Geological facts

Amethyst is the February birthstone and the purple variety of quartz. Heating can change it to yellow-orange citrine or produce ametrine when color zoning is present.

Field identification & locations

Identify it by purple quartz crystals with hexagonal terminations, glassy luster, hardness sufficient to scratch glass, and absence of cubic cleavage. Major sources include Brazil, Uruguay, Zambia, Namibia, and Morocco.