gemstone

Tumbled amethyst quartz

Quartz, SiO₂; purple variety colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with vitreous luster, conchoidal fracture, no cleavage, and trigonal crystal structure. The rounded, glossy surface indicates tumbling and polishing; internal fractures and color zoning are visible.

Identified September 8, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich fluids deposit quartz in cavities of volcanic rocks, especially basaltic geodes; purple color develops from iron-related defects and natural radiation. Most gem amethyst formed in cavities during later hydrothermal stages, commonly in Mesozoic–Cenozoic volcanic terrains.

Uses & applications

Used for inexpensive jewelry, carvings, ornaments, metaphysical objects, and mineral collections; large geodes and polished pieces are decorative.

Geological facts

Amethyst is February’s birthstone and is the most valued purple quartz variety. Heating can turn some amethyst yellow or orange, producing citrine-like material.

Field identification & locations

Identify by its purple color, glassy luster, hardness, and inability to scratch with a steel nail; quartz should scratch ordinary glass. Common sources include Brazil, Uruguay, Zambia, Bolivia, and Mexico.