gemstone

Tumbled amethyst

Amethyst, purple quartz (SiO₂) colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; vitreous luster; purple to lilac color with translucent clarity; trigonal crystal structure, typically lacking visible cleavage and showing conchoidal fracture. The rounded shape and polish indicate human tumbling.

Identified August 31, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in cavities and fractures of volcanic rocks, especially basalt, when silica-rich groundwater deposits quartz over long periods. Most amethyst formed during the Cenozoic or older hydrothermal episodes; exact age depends on locality.

Uses & applications

Used for inexpensive jewelry, carvings, décor, metaphysical collections, and polished stones. It is less commonly used industrially than ordinary quartz.

Geological facts

Purple color ranges from pale lavender to deep violet and may fade with prolonged intense sunlight or heat. Distinctive zoning, natural crystal faces, or a quartz-like fracture help distinguish it from purple glass.

Field identification & locations

Common sources include Brazil, Uruguay, Zambia, Bolivia, and Mexico. Check for natural color zoning, inclusions, bubbles (usually absent), and coolness relative to plastic; a quartz hardness test can scratch glass but may damage the specimen.