Create your own crystal geode – a round rock containing a crystal-filled cavity. First, cast a plaster geode shell in the mould and then fill it with a crystal-growing alum salt solution. The crystal solution contains an ultraviolet light. An ultraviolet flashlight with holder, as well as a display stand for the geode, are included. Display your beautiful specimen day and night! Learn about how crystals form and why the pigment glows under ultraviolet light.