mineral

Amethyst quartz cluster

Quartz, SiO₂; purple variety colored mainly by iron impurities and irradiation

AI-generated identification · may be incorrect

Mohs hardness 7; translucent purple with vitreous luster and hexagonal prismatic crystals, commonly showing conchoidal fracture and no cleavage. Density is about 2.65 g/cm³; the specimen appears naturally crystalline with a rough, partially druzy matrix.

Identified August 10, 2026More mineral →

Explore Amethyst quartz cluster in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids or groundwater deposit quartz in cavities and fractures, with iron producing the violet color. Most commercial amethyst formed in volcanic cavities during the Cenozoic, especially in Brazil and Uruguay, though ages vary by locality.

Uses & applications

Used as a collectible mineral and gemstone; faceted amethyst is common in jewelry, while clusters and geodes are used decoratively. Common specimens usually have modest market value.

Geological facts

Amethyst is the birthstone for February and is the purple member of the quartz group. Heating can turn it yellow-orange, producing citrine or ametrine-like material.

Field identification & locations

Identify it by purple color, glassy luster, quartz hardness, and six-sided crystal points; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, Zambia, Mexico, and the United States.