mineral

Amethyst quartz geode

Quartz, SiO₂; purple coloration from irradiation and trace iron

AI-generated identification · may be incorrect

Violet, translucent-to-transparent quartz crystals with vitreous luster, six-sided crystal forms, and conchoidal fracture; Mohs hardness 7, specific gravity about 2.65. The gray-brown outer material is likely chalcedony, quartz, or host rock.

Identified August 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing quartz crystals over long periods, commonly in Cretaceous–Cenozoic volcanic terrains. The purple color develops through iron impurities and natural radiation.

Uses & applications

Used for lapidary specimens, carvings, display pieces, and jewelry; lower-grade material is cut into geodes, bookends, and decorative objects.

Geological facts

Amethyst is the purple variety of quartz and is the traditional February birthstone. Heating can turn it yellow-orange, producing citrine-like material.

Field identification & locations

Identify by purple quartz crystals, glassy luster, hardness sufficient to scratch ordinary glass, and absence of cubic cleavage; common sources include Brazil, Uruguay, Zambia, and Morocco. Stronger, more evenly saturated crystals generally command higher prices.