mineral

Amethyst

Amethyst (Silicon Dioxide - SiO2 with iron impurities)

Hardness: 7 on Mohs scale; Color: Pale violet to deep purple (tumbled); Luster: Vitreous (glass-like); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Pale violet to deep purple (tumbled)
Luster: Vitreous (glass-like)

Identified March 18, 2026More mineral →

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 or as linings inside volcanic geodes (amygdules). The purple color results from irradiation, iron impurities, and the presence of trace elements. Age varies by location, often associated with Cretaceous basalt flows in Brazil/Uruguay.

Uses & applications

Primarily used in jewelry, ornamental carvings, and as a popular specimen for gemstone collectors. Industrially, it has been used in glassmaking and abrasives due to its hardness.

Geological facts

Formerly considered one of the 'Cardinal Gems' along with diamond and ruby until large deposits were found in South America. The name comes from the Greek 'amethystos', meaning 'not intoxicated', as it was anciently believed to prevent drunkenness.

Field identification & locations

Identify in the field by its purple hue and inability to be scratched by steel. Commonly found in Brazil, Uruguay, Madagascar, and Ontario. Collectors should look for saturated color and clarity in tumbled stones.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral