gemstone

Tumbled amethyst

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; purple to violet, vitreous luster, trigonal crystal structure, indistinct cleavage, and specific gravity about 2.65. The rounded, glossy surface indicates tumbling and polishing.

Identified August 16, 2026More gemstone →

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Physical properties

Mohs hardness 7; purple to violet, vitreous luster, trigonal crystal structure, indistinct cleavage, and specific gravity about 2.65. The rounded, glossy surface indicates tumbling and polishing.

Formation & geological history

Forms in cavities and fractures of volcanic rocks as quartz crystals, commonly during hydrothermal activity; deposits range from Paleozoic to Cenozoic in age. Major sources include Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used for inexpensive jewelry, carvings, ornaments, and mineral collecting; polished tumbles generally have modest commercial value.

Geological facts

Amethyst is the February birthstone and the purple variety of quartz. Heat treatment can turn it yellow or orange, producing citrine-like material.

Field identification & locations

Identify it by its purple color, glassy luster, hardness, and lack of obvious cleavage; glass is softer and may show bubbles. Typical locality material occurs in basalt geodes and hydrothermal veins.