Published online by Cambridge University Press: 14 March 2018
One of the most outstanding contributions to petrogenesis and a continuing basis for petrologic argument is the classic reaction relation first propounded by Bowen (1922, 1928). This pregnant summary of petrogenetic process, included in a reaction series, has received affirmation anew from the more recent approach of crystal chemistry and atomic structure of the minerals emphasizing the concept of continuous and discontinuous reaction (Brammall, 1936). The evidence upon which this reaction relation was initially proposed is essentially twofold, firstly a thorough acquaintance with the regular association of certain minerals, particularly the essential and varietal minerals, in igneous rocks and this stemmed mainly from microscopic study, whereas the second line of evidence comprises the guidance received from laboratory synthesis of mineral aggregates (simplified rocks) from prepared melts.