mineral

Amethyst cluster

Quartz, silicon dioxide (SiO₂), purple variety

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, hexagonal crystal structure, and no true cleavage; purple color comes from iron impurities and irradiation. The specimen shows purple quartz crystals on a pale, likely quartz or feldspar matrix.

Identified September 4, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in cavities of volcanic rocks, especially basaltic geodes, when silica-rich hydrothermal fluids deposit quartz. Most gem amethyst formed during the Cenozoic or Mesozoic, though ages vary by locality.

Uses & applications

Used for jewelry, carvings, mineral specimens, and décor; high-quality transparent crystals are faceted, while clusters are collected or displayed.

Geological facts

Amethyst is February’s birthstone and becomes yellow-orange citrine when heat-treated. Color commonly fades with prolonged sunlight or heating.

Field identification & locations

Identify it by purple, glassy, six-sided quartz crystals that scratch glass but are not scratched by a steel knife; unlike fluorite, it lacks prominent cleavage. Common sources include Brazil, Uruguay, Zambia, and Bolivia.