This geode formed million of years ago during volcanic eruptions. Volcanic geodes were formed when the volcanic lava flows left cavities filled with gas. As the flows cooled, these cavities allowed for mineral bearing solutions to enter and the combinations of these solutions along with heat, pressure and million of years allowed the geode to form. Whatever minerals were present in the solutions determined what type of minerals and colors would form on the inside. Geodes will resemble a potato on the outside, the stone must then be cut to see the beautiful crystals and colors inside.