mineral

Amethyst Geode

Silicon Dioxide (SiO2) with iron impurities

Hardness: 7 on the Mohs scale; Color: Pale lilac to deep purple; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal prisms; Cleavage: None; Specific gravity: 2.65

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

Identified March 28, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale; Color: Pale lilac to deep purple; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal prisms; Cleavage: None; Specific gravity: 2.65

Formation & geological history

Formed in igneous environments when gas bubbles in cooling lava become cavities. Over millions of years (Cretaceous to present), silica-rich hydrothermal fluids seeped into these voids, crystallizing into quartz. The purple hue is caused by irradiation of iron impurities.

Uses & applications

Predominantly used as decorative display pieces, for metaphysical/lapidary purposes, and high-quality individual crystals are cut into gemstones for jewelry.

Geological facts

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

Field identification & locations

Identify by the rough, basaltic outer 'rind' and the presence of internal crystalline points facing inward. Commonly found in Brazil, Uruguay, and Morocco. In the field, look for round, heavy-for-their-size rocks that sound slightly hollow when tapped.

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