Overview of stable stratification of the mantle as a function of composition for a case with K_D = 0.35 and Δρ_crit = 225 kg m⁻³ and a case stimulating layering, with K_D = 0.1 and Δρ_crit = 150 kg m⁻³. Red dots indicate stable stratification in both cases, blue dots in neither case, and green dots only in the latter case. Composition is shown in terms of molar FeO, MgO and SiO₂ abundances, for a range of 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 composition of the Earth mantle from McDonough (2003) is shown as a yellow diamond.