Principles of rational classification of magmatic rocks
- Saint-Petersburg State Mining Institute (Technical University)
The classification of igneous rocks approved in Petrographic code is not quite good, as well as the classification offered by the commission of the International Union of geological sciences. The rational and practically convenient classification of igneous rocks must take into account positive aspects of existing systematics. The division of igneous rocks into three classes (plutonic, volcanic and hypabissal) according to criteria stated in Petrographic code is well founded. The further division should be based on mineral contents; chemical composition should be used only if mineral contents can not be determined. Chemical composition must be recalculated to contents of normative minerals for classification purposes.