mineral

Amethyst cluster

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent purple to lilac with white quartz, vitreous luster, hexagonal crystal structure, and no true cleavage (conchoidal fracture). The specimen appears as a rough crystalline cluster, possibly with minor iron-oxide staining.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basalt, where quartz crystals grow inward. Most deposits are Cenozoic to younger, though amethyst occurs in rocks of many ages.

Uses & applications

Used for jewelry, ornaments, polished specimens, and mineral collecting; large geodes are decorative. Common specimens typically sell for about $10–$50, while especially vivid, well-formed pieces may reach $100–$300.

Geological facts

Amethyst is the birthstone for February and becomes yellow or orange citrine when heat-treated. Its purple color can fade with prolonged strong sunlight or heating.

Field identification & locations

Identify it by purple transparent-to-translucent quartz crystals, glassy luster, hardness near 7, and lack of cleavage; it scratches glass but not easily steel. Important sources include Brazil, Uruguay, Zambia, Namibia, and Mexico.