gemstone

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; purple coloration from iron-related defects and irradiation; vitreous luster, trigonal crystal structure, and conchoidal fracture rather than cleavage. The specimen is polished/tumbled and appears translucent to opaque with uneven violet zoning.

Identified August 28, 2026More gemstone →

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Physical properties

Formation & geological history

Forms mainly in cavities and geodes of volcanic rocks when silica-rich hydrothermal fluids deposit quartz; the purple color develops during irradiation and trace-element processes. Most gem amethyst is geologically young relative to Earth, commonly associated with Mesozoic–Cenozoic volcanic provinces.

Uses & applications

Used for cabochons, beads, carvings, and inexpensive jewelry; also collected as a mineral specimen and sometimes used decoratively.

Geological facts

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

Field identification & locations

Identify it by its glassy luster, hardness, purple zoning, and lack of cubic cleavage; glass and fluorite are common look-alikes. Major sources include Brazil, Uruguay, Zambia, Namibia, and Mexico.