Book excerpt: This book is the product of 50+ years of hands-on physiochemical work with both ferrous and nonferrous metals and with the metallurgy of refining, extracting, and casting. Its purpose is to cover the various methods of recovery and refining of precious metals. Both primary sources (placer gold, black sand, and ores) and secondary sources (scrap jewelry, electronic scrap, old films, buffings, spent plating and stripping solutions, catalytic automobile converters, and old eyeglass frames) are covered. The information contained in this volume is very basic and is intended for hands-on application and use. It is for nonchemist and chemist alike. I will not discuss the mathematical formulas for the various chemical reactions that take place-I leave them to the reader who wants to increase his working knowledge and understanding of chemistry. There are many courses offered in chemistry and extractive metallurgy, as well as a number of books available for self-study. The purpose of this book is to teach you how to perform various extractive, refining, and testing operations on precious metals (in various forms and states), with a resulting end product. You will learn how to perform operations in assaying and extraction, qualitative analysis, quantitative analysis, testing, classifying, and concentration-some of a purely mechanical nature, some of a chemical nature.