Winemaker Gustav Heineman discovered the largest geode, filled with celestine crystals and measuring over 10 meters across, on South Bass Island, Ohio, in 1897. The geode formed during the Silurian period, around 430 million years ago, when glaciers melted at the end of the last ice age. Lake Erie water seeped into anhydrite pockets, dissolving them and creating caves.
Related Posts
How Two Mummies Rewrote the History of the Green Sahara
Genomic analysis of two 7,000-year-old mummies reveals the inhabitants of the once-lush "Green Sahara" were a genetically isolated population who adopted new technologies through cultural exchange rather than interbreeding.
September 6, 2025
We can use drones to get inside and learn more about active, gassy volcanoes
An overhead shot of a volcano crater in east Java, Indonesia. (Shutterstock) Fiona D’Arcy, McGill University Volcanic eruptions…
October 6, 2022
Scientists have found evidence of past extreme solar storms. Their return could be disastrous for our technology based societies
NASA Solar Dynamics Observatory, Atmospheric Imaging Assembly Maarten Blaauw, Queen’s University Belfast; Ilya Usokin, University of Oulu, and…
October 1, 2024
Rising sea levels may threaten 70% of Africa’s heritage sites by 2050
Among the most exposed cultural sites are the iconic ruins of Tipasa in Algeria. Shutterstock Joanne Clarke, University…
March 25, 2022
