The mineralogy and chemistry of the Caralue, Mundrabilla and Witchelina meteorites

Abstract

Three meteorites have been analysed, petrologically and mineragraphically described. Two, Caralue and Mundrabilla, are medium octahedrites; Caralue is a genuinely low sulphur meteorite, while Mundrabilla is exceptionally high in sulphur, phosphorus, chlorine, carbon and contains accessory silicates. Eight primary minerals have been found in Caralue and eleven in Mundrabilla. Mineragraphic investigations show interesting crystallisation and deformation events in the two irons. The third meteorite, Witchelina, is a highly-weathered Olivine-Bronzite-Chondrite with a high content of ferric oxide. Nine primary minerals were found in Witchelina, while all three meteorites contain pentlandite, goethite and magnetite formed by weathering.

Sampling and analytical methods are discussed, as are the relationships between composition and mineralogy for the siderites and aerolite. It is concluded that X-ray fluorescence is a suitab1e analytical method for S, P and Cl in irons, and for the determination of Si, Ti, Al, Cr, total Fe, Mn, Ca, P, Mg, S and Cl in aerolites. Atomic Absorption Spectroscopy is a valuable technique for determining Ni, Co, Cu, Zn, Cr and Mn in siderites and aerolites.