Grow 13 sparkling Geodes , Crystal Clusters , and Single Crystals up to 8" (20 cm) in diameter. Discover a hidden “CRYSTAL CAVE” over 2,400 feet (800 meters) below the Earth's surface. Learn how crystal salts and casting plaster are mined. CRYSTAL CAVE ® is easy, fun and educational. Mix the casting plaster with water, and make your very own geode shells. Add water to the crystal salt, heat it up (no boiling hot water required – patented process uses only solutions below 132°F / 55°C), and grow your very own crystal clusters, geodes, right before your eyes. A hands-on activity kit for ages 10 and up. Crystals and crystal growing powder are biodegradable. Contents: Crystal growing powder, geode mold, casting plaster, crystal growing containers, lids, stirring rods, caves booklet, instructions. USA: Ages 10 + WARNING: This kit contains chemicals which may be harmful if misused. Read cautions on individual containers carefully. Not to be used by children except under adult supervisions. Weight 3.4 lb Dimensions 11" height x 17" width x 2.25" depth