Aug 4, 2025
Today’s Exhibit of the Day? It’s one of the largest amethyst geodes in the world! At about 13 ft (4 m) tall and 9,000 lbs (4,082 kg), this giant weighs about as much as three compact cars. It was born when molten magma poured from the Earth’s crust some 135 million years ago. While its dazzling purple crystals might catch your eye, this geode would have originally been composed of colorless quartz—its distinctive amethyst color deriving from millenia of natural radiation, heat, and trace contaminants.
You can spot this geode, and other sparkly specimens, in the Museum’s Mignone Halls of Gems and Minerals!
Photo: D. Finnin/ © AMNH
