There has been a scientific debate about the formation of massive magnetite ore deposits, also known as Kiruna type deposits. While some workers have suggested a hydrothermal origin for these deposits others have suggested that they are formed from iron rich magmas. This work consists of six chapters each one related to the understanding of the origin of iron deposits. In chapter 1 a natural example from Chile is investigated. Chapter 2 experimentally investigates the effects of phosphorous and other volatiles on the melting behavior of andesite. The results show that when more than 12% of...