This book reviews the geochemical and petrological characteristics of the potassic igneous rock complexes and investigates the different tectonic settings in which these rocks occur. The authors provide an overview and a classification of these rocks and attempt to elucidate the geochemical differences between barren and mineralized potassic igneous complexes. Many epithermal gold and porphyry copper-gold deposits are hosted by high-K rocks. Therefore, this book is not only relevant to the academic petrologists working on alkaline rocks, but also to the exploration geologists prospecting for epithermal gold and/or porphyry copper-gold deposits in modern and ancient terranes. The 2nd updated and enlarged Ed. contains new subchapters and 3 chapters have been completely rewritten.