mineral

Amethyst (Tumbled Cabinet Stone)

Silicon Dioxide (SiO2) with iron impurities

Hardness: 7 on Mohs scale; Color: Purple, violet; Luster: Vitreous/glassy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Purple, violet
Luster: Vitreous/glassy

Identified June 24, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Purple, violet; Luster: Vitreous/glassy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in hydrothermal veins or inside volcanic geodes where silica-rich fluids cool. The purple color is caused by irradiation of trivalent iron impurities. Common in basaltic rock cavities.

Uses & applications

Primarily used for jewelry, lapidary art, and metaphysical collecting. Also used as a February birthstone and in decorative ornaments.

Geological facts

Formerly considered one of the Cardinal gems (alongside diamond, sapphire, ruby, and emerald) until the discovery of large deposits in Brazil in the 19th century made it more common.

Field identification & locations

Identify by its distinctive purple hue and lack of cleavage. In the field, look for crystalline clusters inside hollow rounded volcanic rocks (geodes). Common in Brazil, Uruguay, and Zambia.

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Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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

Metamorphic Rock

Green Apatite on Albite

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mineral