Field Guide to North American Rocks Minerals

This is a great field guide. Unfortunately, you won't always be able to find your discoveries in the guide. It's packed with information; however, it's not completely comprehensive. I've been able to identify about 80% of my rocks and minerals using this guide. I guess that's pretty good. The perfect guide would aide in the identification of your entire collection. The photos are great in the book. One reason for trouble with identification of some specimens may be individual variability. Only a few pictures of each example rock and mineral are included in the field guide, and these renditions cannot possibly represent the true spectrum of variation of each individual mineral or rock. I would deifinitely buy it again and consider it an important component in my science library.