The following signs are good indicators you've got a geode on your hands. Geodes are usually spherical, but they always have a bumpy surface. Geodes will sometimes have loose material inside, which can be heard when shaking the rock. You can also tap lightly with a stone or hammer to see if it sounds hollow.

How do I know if I found a geode?

The only way to find out for sure if a rock is a geode is to break it apart by tapping it with a hammer, or have someone cut open the rock with a powerful saw. You'll know once you see the interior and whether or not there is a hollow or solid composition.

Is it rare to find a geode?

Geodes are found throughout the world, but the most concentrated areas are located in the deserts. Volcanic ash beds, or regions containing limestone, are common geode locations. There are many easily accessible geode collecting sites in the western United States, including in California, Arizona, Utah and Nevada.