mineral

Amethyst crystal fragment

Quartz, SiO₂; purple variety colored by trace iron and irradiation

AI-generated identification · may be incorrect

Typically translucent purple with vitreous luster, hexagonal crystal structure, and no true cleavage; Mohs hardness 7 and specific gravity about 2.65. The pictured piece appears partly polished or naturally broken, so crystal faces are indistinct.

Identified August 20, 2026More mineral →

Explore Amethyst crystal fragment 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 fill cavities in volcanic rocks, especially basalt, where quartz grows in gas vesicles and geodes. Most specimens formed in Mesozoic-to-Cenozoic volcanic settings, though age varies by locality.

Uses & applications

Used as a gemstone, ornamental stone, carvings, mineral specimens, and occasionally industrial quartz material. Common commercial sources include Brazil, Uruguay, Zambia, and Morocco.

Geological facts

Amethyst’s purple color can fade with prolonged heat or strong sunlight; heating may produce yellow citrine. Color zoning and quartz-like hardness help distinguish it from purple glass or fluorite.

Field identification & locations

Identify by testing hardness against ordinary glass, observing vitreous luster and pale purple zoning, and checking for quartz-like conchoidal fracture. Common localities include Brazil, Uruguay, Zambia, Bolivia, and Arizona.