mineral

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Hardness: 7 (Mohs scale); Color: Pale lilac to deep purple; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Pale lilac to deep purple
Luster: Vitreous (glassy)

Identified June 1, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Pale lilac to deep purple; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Formation & geological history

Formed in hydrothermal veins or geodes within volcanic rocks when silica-rich fluids cool. The purple color is caused by irradiation of trivalent iron (Fe3+) in the quartz structure. Typical ages range from millions to hundreds of millions of years.

Uses & applications

Widely used as a gemstone in jewelry (rings, necklaces), as decorative omaments, and a popular collector's mineral for display and holistic purposes.

Geological facts

Amethyst is the birthstone for February. In ancient Greek lore, it was believed to prevent intoxication, and its name comes from the word 'amethystos', meaning 'not intoxicated'. Large geodes are frequently found in Brazil and Uruguay.

Field identification & locations

Identify by its characteristic purple hue and hexagonal crystal prisms with pyramid-shaped terminations. It can be distinguished from glass by its hardness (it should scratch glass) and lack of air bubbles. Common in geodes and volcanic gas cavities.