Turbulent diffusion coefficient in a 0.50    M_⊙ model. The left axis is for the diffusion coefficient and the right axis for the Fe mass fraction. The coefficient is anchored at a mass ΔM₀ = 10^-7.5    M_⊙. The vertical dashed line is at ΔM₀. The Fe mass fraction, X(Fe), is nearly constant from the surface down to ΔM = 10^-7    M_⊙, which corresponds to Fe being mixed down to approximately 3 × ΔM₀.