The Ni, Fe and Co contents of metal phases in the Allende, Holbrook and Nuevo Mercurio chondrites

The Ni, Fe and Co contents of metal phases in the Allende, Holbrook and Nuevo Mercurio chondrites have been obtained using an automated electron microprobe fitted with both wavelength and energy dispersive spectrometers. Co contents of kamacite in these chondrites are inconsistent with those reported previously, but the general tendency of Co to increase in the kamacite in chondrites from H, L to LL groups, is supported by the study. Although the variation patterns of Ni-Co observed so far for L4, H5 and CV3 chondrites are simple, six L6 chondrites, including those reported previously, show significant difference in Co contents and the concentration and abundance charcateristics of Ni-Fe-Co patterns of the metal phases. The great similarity of composition of each region of these patterns obtained from two samples of Holbrook and two samples of Allende which came from different collections, indicate that the variation patterns of Ni-Co in the metal phases provide a means of characterizing or 'fingerprinting', as do the great differences in the variation patterns of Fe-Ni-Co which occur from one chondrite to another or even within the same group and petrologic type.