This fascinating text contains a comprehensive treatise on the attainment of the ability to recognise crystal forms and especially systems almost instantly with the use of few if any instruments. This system of identification includes the study of numerous wooden, cardboard, or plaster models and crystals, together with oral quizzes involving the instantaneous identification of the forms represented on such models, and discussions of the theoretical aspects of the subject. A veritable must-have for serious students of Crystallography, this book is well deserving of a place within any collection of gemmological literature. Chapters included herein comprise: Isometric System, Hexagonal System, Tetragonal System, Orthorhombic System, Monoclinical System, Thiclinic System, Twins, and Miscellaneous Features. This rare book was originally published in 1918 and we are proud to republish it now with a new introduction to the subject.