gemstone

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; vitreous luster; purple, translucent to transparent, with curved conchoidal fracture and no cleavage. It has a trigonal crystal structure, though tumbling has removed its natural crystal faces.

Identified August 30, 2026More gemstone →

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Physical properties

Formation & geological history

Amethyst forms when iron-bearing quartz crystallizes in gas cavities and fractures of volcanic rocks, especially basalt, with irradiation producing the purple color. Most gem material formed during the Precambrian to Mesozoic eras.

Uses & applications

Used for cabochons, beads, carvings, and decorative objects; traditionally marketed as a February birthstone and collector gemstone. It has little industrial use beyond quartz applications.

Geological facts

Color ranges from pale lilac to deep violet and may fade with prolonged heat or sunlight. Chevron banding, zoning, and reddish hematite inclusions can help distinguish natural amethyst from colored glass or synthetic material.

Field identification & locations

Common sources include Brazil, Uruguay, Zambia, and Namibia; identify it by hardness, cool glassy feel, natural color zoning, and absence of bubbles. The pictured specimen is a polished/tumbled piece, so its original locality cannot be determined visually.