Here are some links to online information and photos about geodes:
This Illinois State Geological Survey page has lots of information about geodes found in the state of Illinois: http://isgs.illinois.edu/outreach/geology-resources/geodes-small-treasure-vaults-illinois
These two websites have lots of photos and information about the geodes found near the Mississippi River in Illinois and Iowa (which are often called “Keokuk Geodes”):
- The Geode Gallery: https://www.geodegallery.com/about_keokuk_geodes.xml
- Bill’s Rockhound Blog: http://rockhoundbill.blogspot.com/2015/04/march2015geodes.html
This Indiana State Museum page has information about geodes found in Indiana: https://indianastatemuseum.wordpress.com/2009/01/23/the-secret-of-geodes/
This web page has information and photos of geodes from all over the world (including Dugway, Utah): https://geology.com/articles/geodes/