gemstone

Tumbled amethyst

Quartz, purple variety; silicon dioxide (SiO₂), colored mainly by iron-related defects

AI-generated identification · may be incorrect

Mohs hardness 7; purple, translucent to transparent, with vitreous luster and hexagonal quartz structure. The rounded polish indicates a tumbled specimen; the dark glossy cap may be quartz or surface coating, so exact identification is uncertain from the image.

Identified August 22, 2026More gemstone →

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Physical properties

Formation & geological history

Amethyst forms in silica-rich hydrothermal fluids and volcanic cavities, commonly lining geodes in basalt. Much material is Paleozoic–Mesozoic or younger, with major deposits in Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used for inexpensive jewelry, carvings, polished stones, geodes, and mineral collections; high-quality deeply saturated crystals have greater gem value.

Geological facts

Purple color fades with prolonged heating or strong sunlight. Amethyst is the birthstone for February and is among the most commercially important quartz varieties.

Field identification & locations

Identify by purple color, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; quartz may show conchoidal fracture. Common sources include Brazil, Uruguay, Zambia, and the United States.