This book describes and comments on the results of research devoted to the studies of phase assemblages in the CaO-SiO2-Al2O3-Fe oxides chemical system, their stability and their evolution in our environment (temperature, pressure). Its aim is to be a research support, not only for researchers and development engineers but also more generally for others interested in materials sciences. The book is divided in two parts; the first devoted to a description of ‘the system' using phase diagrams. The second explores the properties and uses of some of the minerals that are in widespread industrial and commercial use. Much of the work presented in this book is fully original and corresponds to the research undertaken by François Sorrentino from his time at the chemistry department of the University of Aberdeen during the early 1970's, to recent years when he has resumed his interest in mineral research, particularly related to the synthesis of calcium silicates and calcium aluminates, and their industrial manufacture.