What does it mean for a metal to be "precious"? These metals are useful and rare, like gold, and that makes them costly! Readers head underground to discover how precious metal form as well as the characteristics that make them desirable such as luster, ductility, and reactivity. The text includes information about well-known metals like silver and gold, and also covers important precious metals such as rhodium and palladium. Full-color photographs and graphic organizers aid comprehension. Sidebars and fact boxes add more information and highlight important science terms and ideas.