mineral

Amethyst

Silicon Dioxide (Quartz variety), SiO2

Hardness: 7 on Mohs scale. Color: Purple to violet, occasionally dark purple. Luster: Vitreous (glassy). Crystal Structure: Trigonal, commonly forming prismatic crystals with pyramidal terminations, often double-terminated as in Herkimer-style or growth-restricted habits. Cleavage: None, exhibits conchoidal fracture.…

Hardness: 7 on Mohs scale
Color: Purple to violet, occasionally dark purple
Luster: Vitreous (glassy)

Identified August 3, 2026More mineral →

Explore Amethyst 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

Formed in hydrothermal veins and gas cavities (vesicles) within volcanic rocks, where silica-rich solutions cool and crystallize over geological time.

Uses & applications

Widely used in jewelry, lapidary arts, decorative items, and metaphysical crystal collections.

Geological facts

Amethyst is the purple variety of quartz. Its color is caused by irradiation, iron impurities, and the presence of trace elements. Historically, it was regarded as a precious gemstone equal in value to ruby and emerald until extensive deposits were discovered in Brazil.

Field identification & locations

Identified by its distinct purple color, vitreous luster, and lack of cleavage with conchoidal fracture. Commonly found in Brazil, Uruguay, Zambia, and the USA.