mineral

Amethyst geode fragment

Quartz, SiO₂; purple color from irradiation-related iron impurities

AI-generated identification · may be incorrect

Amethyst is quartz with Mohs hardness 7, vitreous luster, white-to-purple color, and hexagonal crystal structure; it has indistinct cleavage and specific gravity around 2.65. The specimen appears to be a cut or broken geode section with purple drusy crystals and a gray-green outer rind, possibly including chalcedony or…

Identified August 10, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits quartz crystals in cavities of volcanic basalt, commonly during the Mesozoic or Cenozoic eras. Major sources include Brazil, Uruguay, Zambia, and Mexico.

Uses & applications

Used for jewelry, carvings, mineral displays, metaphysical objects, and polished geode décor; ordinary pieces have modest commercial value.

Geological facts

Amethyst is the purple variety of quartz and is February’s birthstone. Strong heating can turn it yellow-orange, producing citrine-like material.

Field identification & locations

Identify it by its purple, glassy quartz crystals, lack of metallic appearance, and hardness sufficient to scratch glass. Value is typically $10–$40 for a small common fragment, or $50–$200+ for vivid, well-crystallized specimens.