Condensation temperatures (T_C) of Mg and Si, after subtracting a fit to the C/O-dependence of $T_{\text{C}}^{\text{Mg}}$ and $T_{\text{C}}^{\text{Si}}$ (Fig. 4), plotted against the disk Mg/Si ratios. Here, a trend emerges between T_C and the molar Mg/Si ratio of the disk (bottom) for Si, but not for Mg. Solar Mg/Si=1.23 (Asplund et al. 2009) is indicated as a vertical dashed line. Condensation temperatures are derived from condensation sequence calculations at P = 10⁻⁴ bar.