The variety of volcanic activity in the Solar System is widely recognised, yet the majestic sequences of magmatic processes that operate within an active planet are much less well known. Providing an exposition of igneous rocks, magmas and volcanic erupsions, this book brings together magnetic and volcanic data from different tectonic settings, and planets, with explanations of how they fit together. It systematically examines composition, origin and evolution of common igneous rocks, yet also examines a variety of rare magnetic rocks that play a crucial role in the global magma/igneous rock system.