mineral

Amethyst druzy geode slice

Quartz, SiO₂, purple variety (amethyst), with likely chalcedony/banded agate

AI-generated identification · may be incorrect

Violet crystalline quartz lining a cavity, with gray-white translucent banding and brown iron-oxide staining; glassy luster, trigonal crystal structure, no cleavage, conchoidal fracture, Mohs hardness 7, specific gravity about 2.65.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater deposited chalcedony and quartz crystals in volcanic-rock cavities; purple color results from iron impurities and natural irradiation. Typically Cenozoic to Mesozoic in age, depending on locality.

Uses & applications

Used as a decorative specimen, lapidary material, jewelry, and ornamental geode; generally more collectible when crystals are vivid, well formed, and undamaged.

Geological facts

The fine sparkling crystal coating is called druzy. Color intensity can fade with prolonged sunlight or heat.

Field identification & locations

Identify by purple quartz crystals, hardness sufficient to scratch glass, and agate-like concentric banding; common sources include Brazil, Uruguay, Mexico, and the United States.