mineral

Tumbled amethyst

Quartz, purple variety; silicon dioxide (SiO₂), colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Typically translucent purple with vitreous luster and conchoidal fracture; Mohs hardness 7, trigonal crystal structure, no cleavage, and specific gravity about 2.65. The rounded surface indicates tumbling or polishing.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids fill cavities in volcanic rocks, especially basaltic lava flows, where quartz crystals grow over geologic timescales. Major deposits occur in Brazil, Uruguay, Zambia, and Bolivia; individual crystals may range from millions to hundreds of millions of years old.

Uses & applications

Used as a gemstone, ornamental stone, crystal specimen, and in beads, cabochons, and polished pieces. Fine deep-purple material is more valuable than pale or heavily included stones.

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 material.

Field identification & locations

Identify it by purple coloration, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; dyed glass may show bubbles or unnaturally uniform color. This small tumbled piece is likely commercial Brazilian or Uruguayan material.