mineral

Amethyst-bearing quartz

Quartz, SiO₂; purple variety amethyst, commonly in an amethyst-bearing geode or basaltic cavity

AI-generated identification · may be incorrect

Purple to violet, vitreous luster, hardness 7 Mohs, hexagonal crystal structure, indistinct cleavage, conchoidal fracture, and specific gravity about 2.65. The specimen appears to contain druzy or small amethyst crystals with pale quartz matrix.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich hydrothermal fluids fill cavities, especially in volcanic basalt, where quartz crystallizes and trace iron produces the purple color through irradiation. Most commercial material formed in younger volcanic provinces, commonly tens to hundreds of millions of years old.

Uses & applications

Used for jewelry, ornament, carvings, crystal specimens, and decorative surfaces; lower-grade material is widely sold for collecting and metaphysical purposes.

Geological facts

Amethyst’s color can fade with prolonged heating or strong sunlight, and heating may produce yellow citrine-like colors. Color zoning and crystal faces are useful diagnostic features.

Field identification & locations

Common localities include Brazil, Uruguay, Zambia, and Bolivia; identify it by purple transparent-to-translucent quartz crystals with glassy luster and hardness sufficient to scratch ordinary glass. Estimated value: $5–$30 for a small common specimen, or $30–$100+ for vivid, well-crystallized pieces.