mineral

Amethyst Geode

Amethyst (Silicon Dioxide), Formula: SiO2

Hardness: 7 on Mohs scale; Color: Purple, violet, or lavender crystals within a drusy cavity; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Purple, violet, or lavender crystals within a drusy cavity
Luster: Vitreous (glassy)

Identified March 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed when hydrothermal fluids rich in silica deposit crystals inside cavities of volcanic or sedimentary rocks. The purple color comes from iron impurities and natural irradiation. These specific smaller nodules are often from sedimentary or volcanic environments like those in Mexico or Morocco.

Uses & applications

Primarily used for decorative purposes, crystal collecting, metaphysical use, or as semi-precious gemstones in jewelry (necklaces, rings, and earrings).

Geological facts

Amethyst was considered one of the five cardinal gemstones until large deposits were found in Brazil. The name comes from the Greek word 'amethystos,' meaning 'not intoxicated,' as ancient Greeks believed it prevented drunkenness.

Field identification & locations

Identify in the field by looking for 'potato-like' nodules that feel lighter than solid rocks. When cracked open, they reveal a hollow center with crystal points. Common locations include Brazil, Uruguay, Mexico (Las Vigas), and Morocco.

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