On the distribution of major and trace elements between metal and phosphide phases of some iron meteorites

The concentrations of Fe, Ni, Co, P, Cu, Ga, Ge, Mo, Ru, Rh, Pd, W, Ir and Pt in the phosphides and the metal of the coarse octahedrites Campo del Cielo, Canyon Diablo, Cranbourne and Sardis, the coarsest octahedrite Sao Juliao de Moreira and the hexahedrites Braunau and Lombard have been determined by spark source mass spectrometry. Striking differences are observed of the element contents between bulk meteorite and the phosphides as well as between the different phosphide modifications schreibersite and rhabdite. Extreme values are a 20 fold depletion of Ga and a 40 times higher content of Pd in the phosphides. A particularly strong correlation between the noble metal element content and size of phosphide aggregates is observed; it is shown that this correlation is not an artifact of the sample preparation but that is must be real. (orig.)