A treasure ready to be discovered! Geodes were formed millions of years ago when prehistoric volcanoes erupted and gas bubbles were trapped in the lava. The result is a science phenomenon: incredible crystal caverns within each exciting geode. When kids gently hit one of the geodes with a hammer, it will break open to reveal a hidden mineral treasure. Includes full-color guidebook, safety glasses and geodes ranging in size from 1.5"-2". Geodes vary in type and color.