gemstone

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent purple with white quartz veining and cloudy inclusions; vitreous luster, trigonal crystal structure, and conchoidal fracture rather than cleavage. The rounded, glossy surface indicates tumbling and polishing.

Identified September 19, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when iron-bearing quartz crystallizes in gas cavities of volcanic rocks, especially basalt, with irradiation and natural heating producing the purple color. Most gem amethyst formed in Cenozoic to older volcanic environments, commonly tens to hundreds of millions of years old.

Uses & applications

Used for cabochons, beads, ornaments, carvings, and metaphysical collecting; quartz also has major industrial uses in glass, electronics, and abrasives.

Geological facts

Purple color varies with iron content and heat treatment; excessive heating can turn amethyst yellow or brown, producing citrine-like material.

Field identification & locations

Identify by purple quartz, hardness, glassy luster, and conchoidal fracture; common sources include Brazil, Uruguay, Zambia, and Mexico. This specimen appears to be low-to-moderate grade due to fractures and cloudy zoning.