Iron: Whence it came,where it went

Determinations of the abundances of iron and related elements in the photosphere, chromosphere and corona of the Sun and in solar and galactic cosmic rays are reviewed and compared with abundances derived from meteoritic data. Observed Solar System abundances are found to be in accord with predictions of nucleosynthesis under either hydrostatic or explosive conditions but cannot yet be used to define these processes uniquely.Distribution of iron among planets and meteorites can probably be adequately modelled by condensation and fractionation under equilibrium conditions above about 700 K but below that temperature it is likely that inhibited solid state diffusion perturbed attainment of equilibrium. Pertinent factors which are presently unknown include the mechanism responsible for metal-silicate fractionation, the grain size achieved by metallic iron in the nebula and whether iron-bearing silicate formed prior to accretion.Dedicated to Professor Harold C. UreyPublication Number 1560-Institute of Geophysics and Planetary Physics, University of California, Los Angeles.