Here is a book to take into all parts of California on trips and hikes, making you knowledgeable of the rocks and minerals found, and saving hours of time by describing and picturing just those kinds found in this state. Most geologists will tell you that pictures alone can be very misleading whe used to identify rocks and minerals. This is particularly true of color pictures because most rocks and minerals have a bewildering set of colors and only in the metallic minerals is color really important. For this reason it is vital to tie the pictures with clearly developed keys that show how to use hardness, color specific gravity, luster , texture, crystal shapes and so on systematically, to identify what you have found. This is successfully accomplished in the book to increase you ability and understanding as a field collector.