Gr 4–7—Readers will be fascinated by this intermediate series and its appreciation for all things rock. Filled with vibrant images of crystals and gems that jump off the pages, these informative volumes explore the field of geology in easy-to-understand texts; however, some of the content is redundant—the rock cycle appears in several volumes and is even the focus of one of them—or inconsistent. (For instance, Gems states that approximately 200 minerals are classified as gems, whereas Crystals indicates that "only 100 are considered gemstones.") Aligned to Common Core and state standards, the series provides ample opportunity for additional research ("Stop and Think"), hands-on experimentation ("In the Field"), and critical thinking ("Changing Minds") that will have readers looking at the world around them with a better understanding of just what exactly they're seeing. Despite a few issues, these are solid choices.