mineral

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness 7 Mohs; purple to violet coloration, caused mainly by iron impurities and irradiation; vitreous luster, conchoidal fracture, trigonal crystal structure, and no cleavage. The smooth, rounded surface indicates mechanical tumbling and polishing.

Identified August 25, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basaltic lavas; crystals commonly developed in Mesozoic to Cenozoic geodes. Major sources include Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used as a gemstone, ornamental stone, meditation/collecting material, and in polished carvings and geodes. It has modest commercial value unless exceptionally saturated, transparent, or from a notable locality.

Geological facts

Amethyst is the purple variety of quartz and is February’s birthstone. Heating can turn it yellow-orange, producing citrine or ametrine-like colors.

Field identification & locations

Identify by its purple quartz appearance, glassy luster, hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Natural color zoning and internal fractures help distinguish it from glass or dyed stones.