mineral

Tumbled amethyst

Quartz, SiO₂; purple variety colored mainly by iron-related defects

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple to violet with darker patches, vitreous luster, no obvious cleavage, conchoidal fracture, and hexagonal quartz crystal structure. The rounded surface indicates tumbling and polishing.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Forms in cavities of volcanic rocks, especially basalt, when silica-rich hydrothermal fluids deposit quartz and trace iron; coloration develops through irradiation and heating. Individual deposits range from relatively young to Precambrian in age.

Uses & applications

Used for ornamental stone, cabochons, jewelry, carvings, and mineral collecting. Common tumbled pieces are inexpensive.

Geological facts

Amethyst is the purple member of the quartz family and is February’s birthstone; heating can turn some amethyst yellow or orange, producing citrine-like material.

Field identification & locations

Commonly found in Brazil, Uruguay, Zambia, Namibia, Mexico, and the United States. Identify it by purple quartz-like translucency, glassy luster, hardness that scratches glass, and lack of strong cleavage; the image alone cannot exclude dyed quartz or another purple stone.