gemstone

Tumbled amethyst

Quartz, purple variety — silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with a pale gray-white internal vein or inclusion, vitreous luster, and no visible crystal faces due to tumbling. Quartz is trigonal and has poor cleavage, with conchoidal fracture; specific gravity is about 2.65.

Identified August 31, 2026More gemstone →

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Physical properties

Formation & geological history

Amethyst forms when trace iron in silica-rich fluids colors quartz during oxidation and irradiation, commonly in volcanic gas cavities and hydrothermal veins. Most commercial material formed in Mesozoic–Cenozoic volcanic environments, though its exact age depends on locality.

Uses & applications

Used for cabochons, beads, carvings, metaphysical items, and collector specimens; it is also February’s birthstone. Common tumbled pieces have modest value unless color, clarity, and provenance are exceptional.

Geological facts

The purple color can fade with prolonged heat or intense sunlight. The pale zone may be quartz, chalcedony, or a healed fracture/inclusion; photography alone cannot confirm whether the specimen is naturally amethyst or treated quartz.

Field identification & locations

Identify it by purple color, glassy luster, hardness near 7, and inability to scratch it with a steel knife while scratching ordinary glass. Common sources include Brazil, Uruguay, Zambia, and Bolivia.