We have investigated the distribution of Mg, Fe, Al, and Cr among olivine, orthopyroxene, spinel, and liquid in the system MgO–FeO–Fe2O3–Al2O3–Cr2O3–SiO2for temperatures from 1309° to 1471°C under an atmosphere of constant CO2/H2= 10/1 at a total pressure of 1 atm. Crystal–liquid and crystal–crystal distribution coefficients defined (with Fe and Mg as examples) in the formKc‐liqD= (Fe2+/Mg)crystal/(Fe2+/Mg)liquid, andKc‐cD= (Fe2+/Mg)crystal 1/ (Fe2+/Mg)crystal 2, were calculated from the experimental data. The crystal‐liquid coefficients for the silicate minerals are relatively constant [Kol‐liqD(Fe2+/Mg) =0.33;Kopx‐liqD(Fe2+/Mg) = 0.29]. However, the crystal‐liquid coefficient for spinel is more variable [Ksp‐liqD(Fe2+/Mg) =1.2 to 1.7]. Chromium is strongly partitioned into spinel relative to coexisting liquid, olivine, and orthopyroxene (Dsp‐liqCr= 80 to 170,Dsp‐olCr= 100 to 230, andDsp‐opxCr= 60 to 120), and Al is enriched in the liquid and the spinel relative to olivine and orthopyroxene. Values of (Al/Cr)opx/(Al/Cr)sprange from 4 to 8. The experimental results also show that the Al/Cr ratio in spinel increases with decr