This introduction to ionic compounds is designed for the reader who wants a better understanding of the concepts that are used by the chemist and mineralogist in their attempts to unravel the mysteries of nature. The emphasis on the relationship of structure at the atomic level to the symmetry and properties of crystals will be of particular interest to those interested in mineralogy. The book requires no knowledge of chemistry or mineralogy beyond that obtained in a typical secondary school curriculum. It is designed to appeal to the mineralogy student who wants to delve more deeply into the relationships between structure and bonding at the atomic level and the macroscopic properties of minerals. It should also appeal to the serious mineral collector who wants to learn more about the chemical and crystallographic properties of his collection. Finally, the author hopes that the book will be of value to those students of geology who want to bolster their understanding of chemistry.