Introduction to phoscorites: occurrence, composition, nomenclature and petrogenesis

The first response to the title of this book is often 'What is a phoscorite?'. The exact definition and characteristics of phoscorite are discussed in some detail in Chapter 2 and were the subject of varying opinions amongst the authors of this and other chapters. We nicknamed the book 'the dark side of carbonatites', which covers it nicely. Phoscorites are dark, often very handsome, sometimes economically valuable, magnetite-apatite-silicate rocks, almost always associated with carbonatite. They are key to understanding the longstanding question of how carbonate and carbonate-bearing magmas rise to the crust and the Earth's surface. Despite this, they have been given little attention; a search on geological literature databases will produce thousands of references to carbonatite (up to 4125 on Georef) but not more than thirty references to phoscorite. This book goes some way to redress this balance. Over the last ten years many European and North American scientists have studied Kola rocks in collaboration with Russian colleagues. The idea for this book came from one such project funded by the European organisation, INTAS (Grant No 97-0722). The Kola Peninsula, Russia, is one of the outstanding areas in the World for the concentration and economic importance of alkaline rocks. However, Russian work on the Kola complexes is still relatively