Predicted stratification of the mantle after overturn as a function of bulk mantle composition in terms of molar MgO, FeO, and SiO₂, assuming Δρ_crit = 225 kg m⁻³. Blue and red dots denote cases with density differences across the mantle smaller than and larger than Δρ_crit (i.e., with a well-mixed and stably stratified mantle), respectively. Composition is shown for a range of bulk mantle Mg/Si from 0.05 to 20, and FeO from 1 to 20 wt%. The 1σ and 2σ ranges of Mg/Si-ratios from the Hypatia catalog are shown as vertical dashed and dot-dashed lines, respectively. Green dots on these lines correspond to compositions shown in Table 1. The yellow diamond shows Earth’s mantle composition (McDonough 2003).