mineral

Tumbled citrine (likely heat-treated amethyst)

Quartz, SiO₂

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent yellow-to-honey color, vitreous luster, and conchoidal fracture. Quartz is trigonal and has no cleavage; the rounded shape is from tumbling and polishing.

Identified August 30, 2026More mineral →

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Physical properties

Hardness 7 Mohs; translucent yellow-to-honey color, vitreous luster, and conchoidal fracture. Quartz is trigonal and has no cleavage; the rounded shape is from tumbling and polishing.

Formation & geological history

Quartz forms in hydrothermal veins and cavities, commonly in igneous rocks; natural citrine is relatively rare, while much commercial citrine is heat-treated amethyst. Quartz spans many geological ages and settings.

Uses & applications

Used as an ornamental and jewelry gemstone, lapidary material, and collector specimen. This small tumbled piece has modest commercial value.

Geological facts

Orange-brown zoning or a reddish base often suggests heat-treated amethyst rather than natural citrine. It may be confused with yellow calcite, but quartz is substantially harder and does not fizz in dilute acid.

Field identification & locations

Common sources include Brazil, Uruguay, Madagascar, and Zambia; amethyst-to-citrine treatments are especially associated with Brazil. Field tests include hardness against steel or glass and checking for quartz-like conchoidal fracture, though destructive testing is not recommended.