Experience the thrill of cracking open your own geodes! You will receive four to five approx. golf ball size geodes with instructions for cracking. Two different kinds of geodes are included that have varying types of crystals. These geodes are composed of Rhyolite, Agate, and Quartz. These beautiful hollow geodes were formed from volcanic activity. Over thousands of years trapped gas inside the cavity and moisture seepage caused crystal formations to grow.