mineral
Amethyst-bearing quartz
Quartz, SiO₂; purple coloration from trace iron and irradiation
AI-generated identification · may be incorrectHardness 7 Mohs; translucent gray-white to violet, with vitreous luster and typically conchoidal fracture. The specimen appears massive or granular rather than showing distinct crystal faces; cleavage is absent, and specific gravity is about 2.65.
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Physical properties
Hardness 7 Mohs; translucent gray-white to violet, with vitreous luster and typically conchoidal fracture. The specimen appears massive or granular rather than showing distinct crystal faces; cleavage is absent, and specific gravity is about 2.65.
Formation & geological history
Forms when silica-rich hydrothermal fluids deposit quartz in cavities and fractures, commonly in volcanic basalt and geodes. The purple color develops from iron impurities and natural radiation, generally during relatively young to ancient geological processes depending on the host rock.
Uses & applications
Used as a gemstone, ornamental stone, mineral specimen, and source material for carvings and polished pieces. Small rough fragments have modest commercial value.
Geological facts
Amethyst is the purple variety of quartz and is the February birthstone. Its color can fade with prolonged heating or strong sunlight, while heating may produce yellow-orange citrine.
Field identification & locations
Identify it by purple zones, glassy luster, hardness sufficient to scratch ordinary glass, and lack of cleavage; avoid confusing it with purple glass or fluorite. Common sources include Brazil, Uruguay, Zambia, and Mexico.
