gemstone

Likely tumbled amethyst

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent violet-purple color, vitreous luster, trigonal crystal structure, and indistinct cleavage with conchoidal fracture. The rounded, glossy form indicates tumbling or polishing.

Identified August 25, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when iron-bearing quartz in volcanic cavities is irradiated and develops purple color, commonly in basalt geodes. Major deposits occur in Brazil, Uruguay, Zambia, and Mexico; ages vary from Mesozoic to younger volcanic settings.

Uses & applications

Used in jewelry, ornaments, carvings, and mineral collections; small tumbled stones have modest decorative value.

Geological facts

Purple color results mainly from radiation-induced defects involving iron. Heating can remove the purple color or produce yellow-orange citrine-like material.

Field identification & locations

Identify by its purple quartz appearance, glassy luster, hardness, and lack of fizz in dilute acid; the photograph alone cannot exclude dyed glass or another purple mineral. Common locations include basalt geodes and hydrothermal veins.