This book is a comprehensive treatment of fine particle magnetism and the magnetic properties of rocks. Starting from atomic magnetism and magnetostatic principles, the authors explain why domains and micromagnetic structures form in ferrimagnetic crystals and how these lead to magnetic memory in the form of thermal, chemical and other remanent magnetizations. One chapter is devoted to practical tests of domain state and paleomagnetic stability. Another deals with pseudo-single-domain magnetism, i.e., particles that contain domain walls but behave like a single domain. The final four chapters place magnetism in the context of igneous, sedimentary, metamorphic, and extraterrestrial rocks. This book will appeal to researchers in the earth sciences, physics, and engineering.