gemstone

Amethyst crystal cluster

Quartz (SiO₂), purple variety colored mainly by iron-related defects and irradiation

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, transparent to translucent purple crystals, and conchoidal fracture; quartz has a trigonal crystal structure and no true cleavage. The specimen appears to be a small natural druzy or cluster on a darker matrix.

Identified September 5, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basalt and rhyolite, where quartz crystals grow over geologic time, commonly in the Cenozoic to older volcanic settings.

Uses & applications

Used as a jewelry and ornamental gemstone, mineral specimen, and lapidary material; lower-grade clusters are popular for décor and collecting.

Geological facts

Purple color ranges from pale lilac to deep violet and can fade with prolonged heat or strong sunlight. Amethyst is the traditional February birthstone.

Field identification & locations

Identify by its purple color, glassy luster, hexagonal crystal points, hardness, and lack of cleavage; common sources include Brazil, Uruguay, Zambia, and Mexico. The visible gray base may be quartz or volcanic matrix.