"They're sparkly with varied hues. You might see them in a beautiful necklace, a breathtaking ring, or even in a computer. They're gems! Gems are some of Earth's most precious resources, and some of them are millions -- or even billions -- of years in the making. This detailed text, accompanied by colorful photographs, informs readers about the remarkable processes that take place under the surface of Earth to form different kinds of gems. They'll...

What makes a metal precious? It's rare, and it's useful. When a metal is both these things, like gold, it's very precious-and expensive. This book takes readers underground where they'll discover the processes and elements that shape precious metals. They'll learn about the features of metals that make them desirable, such as luster, ductility, and reactivity, and how certain metals are utilized. While readers may know something about gold and silver,...