gemstone

Tumbled amethyst

Amethyst, purple quartz (SiO₂), colored by trace iron and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with pale zoning, vitreous luster, trigonal crystal structure, and no cleavage (conchoidal fracture). The rounded shape indicates machine tumbling and polishing.

Identified August 11, 2026More gemstone →

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Physical properties

Mohs hardness 7; translucent purple with pale zoning, vitreous luster, trigonal crystal structure, and no cleavage (conchoidal fracture). The rounded shape indicates machine tumbling and polishing.

Formation & geological history

Forms mainly in cavities of volcanic basalt as quartz-lined geodes, commonly during late-stage hydrothermal activity; deposits range from Paleozoic to Cenozoic in age. Major sources include Brazil, Uruguay, Zambia, and Mexico.

Uses & applications

Used for inexpensive cabochons, beads, carvings, ornaments, and metaphysical collectibles; faceted gem-quality material is used in jewelry. Tumbled pieces have modest commercial value.

Geological facts

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

Field identification & locations

Identify it by its purple color, glassy luster, hardness, and lack of cleavage; quartz will scratch glass but not be scratched by a steel knife. Strong uniform color or very clear material may indicate treatment or synthetic origin.