The distribution of the major elements between vapor and solid has been calculated for a cooling gas of cosmic composition. The assumption is made that high temperature condensates remain in equilibrium with the vapor, affecting the temperatures of appearance of successively less refractory phases. The model suggests that the major textural features and mineralogical composition of the Ca, Al-rich inclusions in the C3 chondrites were produced during condensation in the nebula characterized by slight departures from chemical equilibrium due to incomplete reaction of high temperature condensates. Fractionation of such a phase assemblage is sufficient to produce part of the lithophile element depletion of the ordinary chondrites relative to the cosmic abundances. Iron-nickel alloys have higher condensation temperatures than forsterite and enstatite at all total pressures greater than 7.1 × 10 -5 atmospheres. These data lend support to the origin of the core and mantle of the earth by a heterogeneous accumulation process. The temperature difference between the condensation points of iron and magnesium silicates increases with pressure allowing the possibility of greater fractionation of metal from silicate towards the center of the solar nebula where the pressure and temperature were highest.