I bought this little pocket book for myself and my granddaughter. I've used Mr. Simmons' full-size books for years and was thrilled to find that he'd come out with this version so I could take it along with me. My granddaughter has a new-found delight in crystals and so it was perfect for her to start with. Of course, it doesn't have all the fine information as the larger volumes, but it's a great reference while treasure hunting!