Forsterite-Diopside-Anorthite: A Basaltic Analog

Our models for basalt have so far dealt only with plagioclase and pyroxene, the two dominant minerals in most basalts. We have ignored olivine and calcium-poor pyroxene, but these are fundamentally important minerals in any classification scheme of basalt, and are furthermore centrally involved in our study model, the basalt tetrahedron (Chap. 2 ). The present chapter explores a phase diagram containing iron-free olivine, namely forsterite, thereby illuminating some important principles of rock genesis as well as some simple but useful new principles of phase diagrams.