gemstone

Tumbled amethyst quartz

Quartz, SiO₂; purple coloration from trace iron and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; translucent lavender-purple, vitreous luster, conchoidal fracture, and no cleavage. The specimen is tumbled/polished and shows internal fractures or veils; crystal structure is trigonal.

Identified September 13, 2026More gemstone →

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Physical properties

Formation & geological history

Amethyst forms when iron-bearing quartz crystallizes in volcanic cavities, commonly in basaltic geodes, and later receives natural irradiation. Most commercial material is Cretaceous to Cenozoic, though ages vary by deposit.

Uses & applications

Used as a lapidary stone, jewelry, ornaments, and mineral specimens; this small included tumbled piece has modest collector value.

Geological facts

Color intensity can fade with prolonged heat or strong sunlight. White zones and internal fractures are natural inclusions, not usually evidence of treatment.

Field identification & locations

Common sources include Brazil, Uruguay, Zambia, and Bolivia. Identify it by purple quartz color, glassy luster, hardness that scratches glass, and lack of cleavage; a steel blade should not scratch it.