Further evidence in support of the mixing model for howardite origin

Four diogenites, four howardites and seven eucrites have been analysed for major, minor and a number of trace elements by X-ray fluorescence spectrometry. Inter-element relationships between various elements in howardites, particularly refractory elements, are interpreted in the light of the recently proposed mixing model, whereby howardites are considered to be mixtures of eucritic and diogenitic material. Differences in composition observed between two samples of Frankfort analysed in this work lend strong support to this hypothesis. The nature of the proposed end-member composition in howardites is shown to be variable.