Structure of taenite in two iron meteorites

X-ray and Moessbauer spectral techniques (a conventional spectrometer with a source material of 10 mCi Co-57 in palladium) are used to evaluate the structure of taenite (a Ni-Fe alloy) in two iron meteorites, Toluca and Cape York. Observed spectral asymmetry is considered a result of quadrupole splitting due to the noncubic surroundings of the iron atoms. The lamellae are found to be essentially single crystals, all of which contain the superstructure L10 of FeNi. Attention is given to phase differentiation, reported for both meteorites, in which lattice constants are equal for the alpha and gamma phases. The latter phase is disordered and paramagnetic, resulting from a Ni content lower than 30%.