mineral

Tumbled amethyst with possible lepidolite/colored quartz companion

Amethyst, purple quartz (SiO₂), likely with iron-related color centers

AI-generated identification · may be incorrect

Violet, translucent, glassy-to-waxy luster; hardness 7 Mohs, trigonal crystal structure, no cleavage, conchoidal fracture, specific gravity about 2.65. The rounded piece is polished/tumbled; the smaller vivid-purple stone may be dyed quartz or lepidolite and cannot be confirmed visually.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Amethyst forms when iron-bearing silica-rich fluids fill cavities in volcanic rocks, commonly basalt, where quartz crystals grow over millions of years. Major deposits occur in Brazil, Uruguay, Zambia, and Mexico; exact age depends on locality.

Uses & applications

Used for cabochons, beads, carvings, display specimens, and ornamental objects; fine transparent purple material is used in jewelry. Common tumbled pieces have modest commercial value.

Geological facts

Heating can turn amethyst yellow-orange, producing citrine, while excessive heat may make it pale or colorless. Natural amethyst commonly shows uneven zoning and internal fractures or inclusions.

Field identification & locations

Identify by purple quartz hardness, glassy luster, translucency, and lack of cleavage; it should scratch glass but not be scratched by a steel blade. Typical sources include geodes and basalt cavities in Brazil and Uruguay.