Formation: Geodes are formed naturally by volcanic activity. Bubbles in lava harden, over time natural crystals grow inside of the lave bubbles. What's Inside? Have a great time breaking these geodes open! There are 12 geodes in this pack ranging is size from large marble to bigger than golf ball size. They are hollow geodes. Geode cracking instructions are included; once the geodes are opened use the geode identification guide to determine which minerals you discovered. Amethyst (rare but possible), smoky quartz and clear quartz natural crystals are found inside these geodes! It’s a surprise every time you open one! Ancient Treasure Adventures: An Ancient Treasure is waiting to be discovered!!! We are family owned company with 3 generations of experience exploring and mining geodes. We know quality geodes when we see them. “High Quality Geodes”: These geodes have been carefully sorted to insure that they are almost all hollow. The crystals inside will be consistently clean and sparkly with a variety of colors! Great family fun and educational for the kids! 100% naturally occurring geodes with real, genuine crystals! Not all geodes are equal: A real geode has a good sized hollow pocket inside of it. There are many "Geodes" out there that are technically "Nodules" or completely or mostly solid. Nodules are very inexpensive (cheap) and common. We take pride in selling real geodes and have the best quality of break open geodes in the world! Join us on this Ancient Treasure Adventure!