gemstone

Tumbled amethyst

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

AI-generated identification · may be incorrect

Mohs hardness 7; purple to lavender, with vitreous luster and translucent edges. Hexagonal quartz structure, no cleavage, uneven/conchoidal fracture; specific gravity about 2.65.

Identified September 17, 2026More gemstone →

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Physical properties

Mohs hardness 7; purple to lavender, with vitreous luster and translucent edges. Hexagonal quartz structure, no cleavage, uneven/conchoidal fracture; specific gravity about 2.65.

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basalt, where quartz crystals grow in geodes. Most amethyst is Cenozoic to Mesozoic in age, though deposits span many geological periods.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and mineral specimens; also used in limited industrial quartz applications. Tumbled pieces are inexpensive decorative gemstones.

Geological facts

Color may fade with prolonged heating or strong sunlight; yellow citrine produced by heating amethyst is often marketed as “ametrine” only when naturally showing both colors.

Field identification & locations

Identify by purple quartz color, glassy luster, hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, Zambia, and Siberia.