mineral

Amethyst cluster

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

AI-generated identification · may be incorrect

Hardness 7 Mohs; purple to violet crystals with vitreous luster, hexagonal crystal structure, and indistinct cleavage. Typical specific gravity is about 2.65; the gray-green matrix appears to be druzy quartz with possible chlorite or calcite.

Identified August 20, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basalt and rhyolite; crystals may develop over millions of years, commonly in Mesozoic to Cenozoic volcanic provinces.

Uses & applications

Used as a decorative mineral, lapidary material, jewelry stone, and collector specimen; large attractive clusters have ornamental value.

Geological facts

Amethyst is quartz colored by trace iron and irradiation; heating can turn it yellow-orange, producing citrine. Its purple color may fade with prolonged strong sunlight or heat.

Field identification & locations

Identify by purple, glassy, six-sided quartz crystals that scratch glass but not by a steel blade; common sources include Brazil, Uruguay, Zambia, and Mexico. The specimen is likely a natural amethyst-on-matrix cluster.