Figure F29. Plots showing relationship between Mg# and compatible elements Al2O3 and Cr2O3 and incompatible elements MnO, TiO2, and Na2O in clinopyroxene (cpx). Both Type 1 and Type 2 clinopyroxenes are shown, as well as rock type. Oxide precipitation is well correlated with Mg#s < 73–75, and the appearance of oxides does not appear to be random but systematically increasing as Mg# decreases once this threshold has passed. Oxide precipitation is not predicted at such high Mg#s in perfect fractional crystallization models. Black vertical line correlates with the onset of abundant oxide precipitation or occurrence in the samples.

Figure F29. Plots showing relationship between Mg# and compatible elements (A) Al₂O₃ and (B) Cr₂O₃ and incompatible elements (C) MnO, (D) TiO₂, and (E) Na₂O in clinopyroxene (cpx). Both Type 1 and Type 2 clinopyroxenes are shown, as well as rock type. Oxide precipitation is well correlated with Mg#s < 73–75, and the appearance of oxides does not appear to be random but systematically increasing as Mg# decreases once this threshold has passed. Oxide precipitation is not predicted at such high Mg#s in perfect fractional crystallization models. Black vertical line correlates with the onset of abundant oxide precipitation or occurrence in the samples.