Geology.com has numerous articles about Earth Science World Records. These feature the world’s tallest tsunami, world’s largest volcano, world’s tallest geyser and more. We have learned from these articles that picking the largest, tallest, deepest, etc. will be met with disagreements about measurement methods, qualifying criteria, and more.

Similar problems surround naming “the world’s largest geode”. The definition of a geode, the methods of measuring, the reliability of reports about large geodes – and more – make choosing the “largest” problematic. So, we are going to point to a geode that we think meets the definition and that is quite impressive in size. Some researchers have called it “the world’s largest geode”, and others disagree, but most can agree that this is a really big one.

The “Geode of Pulpi” is located near Almeria, Spain. It has a volume of approximately 11 cubic meters and a width of about 12 meters. It is hosted in Triassic dolostone, and it has a discontinuous mineral sequence that begins with iron-carbonates and barite, followed by celestine, and concluding with an internal cavity into which giant gypsum (selenite) crystals protrude. The gypsum crystals are colorless and transparent and are said to “look like blocks of ice”. The geode was discovered in 1999 when it was intersected by a passage of the Mina Rica silver mine.