Book excerpt: An easy to use field guide that contains everything rock and mineral enthusiasts need to know with more than 1,000 spectacular illustrations—600 in full color! Practical, concise, and easy to use, Simon & Schuster’s Guide to Rocks and Minerals contains everything that the rock and mineral enthusiast needs to know. This field guide is divided into two large sections—one devoted to minerals and one to rocks, each prefaced by a comprehensive introduction that discusses formation, chemistry, and more. All 377 entries, beautifully illustrated with color photographs and helpful visual symbols, provide descriptions and practical information about appearance, classification, rarity, crystal formation, mode of occurrence, gravity of mineral, rock chemistry, modal classification fields, formational environments, grain sizes of rocks, and much more. Whether you are a serious collector or an information-seeking amateur, this incomparably beautiful, authoritative guide will prove an invaluable reference.