Experiments with the laser-heated diamond cell show that (Mg,Fe)SiO3 perovskite reacts chemically with liquid iron at pressures greater than 70 GPa and temperatures above 3700 K. X-ray diffraction analyses of quenched samples demonstrate that the reaction products include SiO2 stishovite and iron alloys (Fe,Mg)xO and FexSiy, at the interface between the Fe and silicate. Our results suggest that similar chemical reactions occur at the Earth's core-mantle boundary, forming chemical heterogeneities composed of silicate-rich and iron alloy-rich regions in the D' layer. This scenario is consistent with seismological observations. ¿ American Geophysical Union 1989