The term geode is derived from the Greek word Geoides which means "earthlike." Geodes are formed when water and gas bubbles are deposited inside igneous rocks. Surrounding environments and locations determine the type of minerals deposited inside. Most common minerals found are Celestite, Agate, Jasper, Amethyst, Chalcedony and Quartz. Due to the natural and individual nature of this gem; size and shape may vary slightly from that imaged.