mineral

Amethyst

Silicon Dioxide (SiO2)

Hardness: 7 on the Mohs scale. Color: Purple to violet, occasionally dark violet or brownish. Luster: Vitreous (glassy). Crystal Structure: Trigonal, commonly forming prismatic crystals with pyramidal terminations, often doubly terminated as seen in Herkimer-style or growth-matrix specimens.…

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

Identified July 29, 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 cavities (vugs or geodes) within basaltic and other volcanic rocks, where silica-rich fluids cool and crystallize over millions of years under the influence of natural irradiation of trace iron impurities.

Uses & applications

Widely used in jewelry, lapidary arts, decorative items, and as highly prized specimens for mineral collectors.

Geological facts

Amethyst was historically considered one of the 'cardinal' precious gems, equal in value to diamond, ruby, and sapphire, until extensive deposits were discovered in Brazil in the 19th century.

Field identification & locations

Easily identified by its characteristic purple coloration, high hardness (scratches glass), and vitreous luster. Commonly sourced from Brazil, Uruguay, Zambia, and parts of the United States.