STUDIES ON AL KIDIRATE AND KAPOETA METEORITES

Mossbauer spectroscopy (20-300 K), magnetic susceptibility measurement s (77-350 K), scanning electron microscopy and X-ray diffraction exper iments have been performed on two meteorite samples: one from an old f an (Kapoeta) and another from a very recent fall (Al Kidirate). The tw o specimens differ in their mineralogy. Chondrules appear to be absent in Kapoeta and it is probably a pyroxene-plagioclase achondrite with ferrohypersthene as the most abundant mineral. On the other hand, the AI Kidirate meteorite is an ordinary chondrite and the specimen consis ts of olivine, orthopyroxene, troilite and kamacite. The Mossbauer mea surements confirm the above characterization, showing a paramagnetic d oublet for the Kapoeta sample and at least two paramagnetic doublets a nd magnetic sextets for the Al Kidirate specimens. The farmer were ass igned to Fe in pyroxene sites, while the latter was assigned to Fe in pyroxene, olivine, Fe-S and Fe-Ni alloys. The difference in the minera logy of the two meteorites has also been reflected in the temperature- dependent magnetic susceptibility. The magnetization and the hyperfine interaction parameters will be discussed in relation to the mineralog y.