Mg2SiO4-CaAl2Si2O8-SiO2 Diagram. Ternary phase diagram for melting the system Mg2SiO4-CaAl2Si2O8-SiO2 at 0.1 MPa pressure based on data from Kushiro (1972). Temperature is in degrees Celcius and composition is in weight pecent. The non-ternary spinel MgAl2O4 field has been removed to simplify the diagram. Melting temperatures of the three minerals forsterite (Di), anorthite (An), and cristobalite are shown, along with temperatures of three binary eutectic points and one peritectic point. Cotectic curves and one reaction curve are shown. The liquidus (saturation) surfaces for each mineral are shown by temperature contours. The spinel and tridymite fields have been removed to simplify the diagram for petrologists in training. A Mg2SiO4-CaAl2Si2O8-SiO2 diagram with these fields show can be found here (**add a diagram and link**). Return to Text