7Learn about different types of rock, how crystals are formed, where gems can be found in the earth's crust, and more. Engaging text, detailed facts, and impressive statistics give children exciting scientific insight into the rocks, crystals, and gems...and the world around them. A glossary at the end of the book helps reinforce the information. Parents, teachers, and librarians will want to collect all of the books in this series to create a very cool first encyclopedia to build early research skills.