Furthermore, an attempt has been made to vitalize the subject as much as possible, and accordingly there are chapters on the importance of mineralogy in modern civilization, on gems and precious stones, and on the production and uses Of the important economic minerals. Numerous photographs and short Sketches of distinguished mineralogists have also been introduced in the hope that they will add a human touch. The chapters on crystallography are based very largely upon the senior author's Essentials of Crystallography, while much of the material in the descriptions of the 150 minerals given in this text has been taken from. His Descriptive Mineralogy. The determinative tables are an abridgment of the authors' Mineral Tables. We are greatly indebted to Mr. George R. Swain, technical expert in photography in the University of Michigan, whose varied experience and unusual skill made the excellent photographs of models and minerals possible; also to Dr. George F. Kunz for valuable assistance in securing a considerable number of very desirable photographs.