gabbro Pl Ol Di SiO2 48.125 50.54 39.19 55.49 Al2O3 15.85 31.7 0 0 FeOt 5.625 0 18.75 0 MgO 16.34 0 42.06 18.61 CaO 12.36 14.36 0 25.9 Na2O 1.7 3.4 0 0