mineral

Amethyst (purple quartz)

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

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent purple to gray-purple, vitreous luster, hexagonal crystal structure, and poor cleavage with conchoidal fracture. The specimen appears rough and partly crystalline, possibly iron-stained or included quartz.

Identified September 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities in volcanic rocks, especially basaltic geodes; coloration develops from trace iron and natural radiation. Most amethyst deposits formed in Phanerozoic volcanic environments, commonly tens to hundreds of millions of years old.

Uses & applications

Used as a gemstone, carving material, ornamental stone, and mineral-collection specimen; lower-grade material is sold as tumbled stone or geode fill.

Geological facts

Amethyst is the purple member of the quartz family and is February’s birthstone. Heating commonly turns it yellow-orange, producing citrine-like material.

Field identification & locations

Identify it by purple color, glassy luster, quartz hardness, lack of strong cleavage, and crystal faces or geode texture; common sources include Brazil, Uruguay, Zambia, and Mexico. A scratch test should be avoided on valuable specimens.