mineral

Tumbled amethyst

Amethyst, purple variety of quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 7; purple coloration from iron impurities and irradiation; vitreous luster, translucent edges, conchoidal fracture, and no cleavage. The rounded, glossy surface indicates tumbling and polishing; visible internal mottling may reflect quartz zoning or inclusions.

Identified August 18, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in cavities of volcanic basalt when silica-rich fluids deposit quartz, commonly during late-stage cooling; crystals can range from millions to hundreds of millions of years old. It is not classifiable as an igneous, sedimentary, or metamorphic rock itself, but occurs in igneous-hosted veins and cavities.

Uses & applications

Used as a gemstone, ornamental material, meditation/collecting specimen, and occasionally in decorative carvings. Tumbled pieces are common, inexpensive jewelry and gift-shop items.

Geological facts

Amethyst is the February birthstone and was historically regarded as protection against intoxication. Its purple color can fade with prolonged strong sunlight or heating.

Field identification & locations

Identify it by purple quartz color, glassy luster, hardness sufficient to scratch glass, and lack of cleavage; avoid confusing it with dyed glass or purple fluorite. Major sources include Brazil, Uruguay, Zambia, and Mexico.