Millions of years ago Indiana was covered by a shallow sea. It is believed that geodes began as crystals that were covered in silica. The initial crystals dissolved and were replaced by other minerals, creating the geodes known today. Most of the geodes in Indiana are in areas that were not covered by glaciers during the ice ages.
Geodes can be found from in the southern third of the state. Popular counties to find geodes include Brown, Monroe, Morgan, Lawrence and Washington. The Hoosier National Forest, south of Bloomington, has geodes that can be collected in the northern portions of the park. Hoosier National Forest does allow for collection of these geodes as long as earth is not disturbed to obtain the geode. The Monroe Reservoir is one of the best known locations to find geodes in the state.
Best Places to Look
When searching for geodes, look along riverbeds, construction sites or other areas that have been eroded away. In some areas geodes can be found along roadways. When searching along roads, make sure your vehicle is parked out of the way so it doesn't disturb traffic. Geodes can also be found anywhere bedrock is exposed in the southern portion of the state.
One of the most productive ways to find geodes in Indiana is to gain permission to hunt rock quarries. These quarries can be difficult to gain access to and permission must be gained from the owners of the quarries to hunt. The Indiana Geological Survey suggests using the IGS publication Directory of Industrial Mineral Producers in Indiana to find information to contact quarry owners.
Geode and fossil hunting are popular pastimes in these southern Indiana counties. Permission must be gained from private property owners, including along streams and rivers, to be able to hunt and collect geodes. Hunting geodes along roadways requires permission from the Indiana Department of Transportation, the state police or local sheriff's office prior to hunting. When planning your hunt, contact local authorities to see whether permission can be granted. In some cases a permit may be granted to prove you have permission to hunt geodes.