mineral

Amethyst cluster

Quartz, SiO₂, purple variety (amethyst)

AI-generated identification · may be incorrect

Hardness 7 Mohs; typically purple with a vitreous luster and hexagonal prismatic crystals, showing no true cleavage and conchoidal fracture. The specimen appears to contain pale-to-deep purple quartz crystals with darker matrix or iron staining.

Identified August 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids or groundwater deposit quartz in cavities and fractures, with trace iron and irradiation producing the purple color. Common specimens formed in volcanic basalts during the Cenozoic, though quartz veins occur across many geological ages.

Uses & applications

Used for jewelry, ornaments, crystal collecting, and lapidary pieces; lower-grade material is sold as clusters or polished décor. It is not generally used as a major construction aggregate.

Geological facts

Amethyst is the traditional February birthstone and the purple variety of quartz. Heating can convert its color to yellow or orange citrine, sometimes producing ametrine where both colors occur naturally.

Field identification & locations

Identify it by purple transparent-to-translucent quartz crystals with glassy luster and hardness sufficient to scratch ordinary glass; violet fluorite is softer and commonly cleaves. Important sources include Brazil, Uruguay, Zambia, and Mexico.