mineral
Tumbled amethyst (likely)
Quartz, SiO₂; purple coloration from irradiation and iron impurities
AI-generated identification · may be incorrectHardness 7 Mohs; translucent purple to gray-brown, vitreous luster, cryptocrystalline to microcrystalline quartz, no cleavage, conchoidal fracture, specific gravity about 2.65. The smooth rounded shape indicates mechanical tumbling and polishing.
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Physical properties
Hardness 7 Mohs; translucent purple to gray-brown, vitreous luster, cryptocrystalline to microcrystalline quartz, no cleavage, conchoidal fracture, specific gravity about 2.65. The smooth rounded shape indicates mechanical tumbling and polishing.
Formation & geological history
Amethyst forms in silica-rich volcanic cavities, commonly lining basaltic geodes, where quartz crystallizes from hydrothermal fluids or groundwater. Individual crystals may be hundreds of millions of years old, depending on the host rock.
Uses & applications
Used as a gemstone, ornamental stone, carved material, and collector specimen; inexpensive tumbled pieces are common in jewelry and metaphysical markets.
Geological facts
Color intensity depends on iron content and irradiation; heating can turn amethyst yellow or orange, producing citrine-like material. The specimen may also be purple chalcedony or dyed quartz, which cannot be confirmed from the photograph alone.
Field identification & locations
Look for glassy luster, conchoidal fracture, translucency, and purple zoning; quartz should scratch ordinary glass but not be scratched by a steel knife. Major sources include Brazil, Uruguay, Zambia, and Bolivia.
