Geodes look like any old round rock until you crack them open to discover the brilliant, crystal cavern in the center. Geodes were formed millions of years ago when prehistoric volcanoes erupted and gas bubbles were trapped in lava. The result is an exciting science phenomenon of crystalline beauty within each geode. Gently strike a geode with a hammer, and it will break open to reveal a hidden mineral treasure. The Break Open Real Geodes Science Kit offers four intact geodes for cracking open. The kit includes: safety glasses, four real geodes, and an 8-page full-color adventure guide.