Change of Chemical Composition of Minerals with Progressive Metamorphism

Abstract

While discussing the diverse facies and subfacies, the changes in mineral assemblages have been stressed; they are caused by the various mineral reactions. The changes in the chemical compositions of the individual minerals, mostly complex solid solutions, are also to be ascribed to the same process. That the iron-rich chlorites are progressively inpoverished in iron to yield finally a magnesian chlorite with prograde greenschist facies metamorphism, has already been pointed out. Similar changes in chemical compositions of many other minerals, contingent on rising metamorphic grade, have been lately established. Attention is drawn succinctly to this new field of mineralogical research, because of its great importance for the genesis of the metamorphic rocks.