iron meteorite, asteroid, siderophile elements, geochemistry, classification
Abstract
I present detailed petrographic descriptions and major- and trace-element data on a set of ten new iron meteorites (irons) from Nortwest Africa and the Atacama Desert (Chile). Part of these data were used to classify the meteorites upon their submission to the Nomenclature Committee of the Meteoritical Society for official approval. The studied irons belong to the following groups: IAB-complex (2 meteorites), IC (1), IIAB (1), IIE (1), IIIAB (1), IVA (1). Three irons do not fall in any compositional group and, therefore, are classified as ungrouped iron meteorites. Based on their structure, the ten irons were subdivided into plessitic octahedrites (1 meteorite), fine octahedrites (2), medium octahedrites (1), coarse octahedrites (1), ataxites (1) and in iron with anomalous structure (4). The distribution of the studied irons among the chemical groups is consistent with what has already been observed by other authors: irons from northern Africa and Antarctica have a high frequency of ungrouped irons and of members of the IAB-complex with respect to irons from other parts of the World. This biased distribution is discussed in relation to the smaller median size of irons from northern Africa and Antarctica in comparison with the rest of the World.
