gemstone

Tumbled amethyst

Quartz, SiO₂; purple variety colored mainly by iron-related defects

AI-generated identification · may be incorrect

Hardness 7 Mohs; vitreous luster; purple coloration with pale-to-dark zoning; trigonal crystal structure, though tumbling removes crystal faces; no prominent cleavage and conchoidal fracture. The small rounded specimen appears polished/tumbled.

Identified September 4, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basalt, where quartz crystals grow in geodes. Most gem amethyst comes from relatively young Phanerozoic volcanic deposits in Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used for inexpensive jewelry, carvings, ornamental objects, and mineral collections. Value depends on color saturation, transparency, size, and provenance.

Geological facts

Amethyst is the February birthstone and was historically valued as a royal purple gem. Heating can turn it yellow-orange, producing citrine or ametrine-like material.

Field identification & locations

Identify by purple quartz-like appearance, glassy luster, hardness sufficient to scratch ordinary glass, and lack of strong cleavage; glass imitations may contain bubbles. Common localities include Brazil, Uruguay, Zambia, and Mexico.