The ideal pocket guide for beginners If you have trouble distinguishing slate from shale then this is the book for you. Perfect for beginners, and a handy field guide for the amateur geologist, What's That Rock or Mineral? beautifully pictures more than 140 rocks and minerals, from agate to tourmaline, and highlights the characteristics that will help you to identify them. For nature lovers everywhere, What's That...? books are compact, portable identification guides that offer a uniquely accessible visual approach. Designed for beginners, but also handy for a more experienced naturalist, the What's That ...? titles are indispensable pocket guides that give you around 150 of the most common and interesting types and show you how to tell them apart.