Acfer 094, a uniquely primitive carbonaceous chondrite from the Sahara

The Saharan meteorite Acfer 094 is a unique type of carbonaceous chondrite. Mineralogical and petrological considerations and O isotopes are unable to distinguish unambiguously between a CO3 vs . CM2 classification. The other important light elements, C and N, have systematics that do not match any previously recognised meteorite group. Particularly important in this respect is the very low C/N ratio and δ 13 C of the macromolecular C. Acfer 094 has more diamond and SiC, especially X type grains, than any other specimen studied, suggesting minimal thermal or aqueous processing to decrease its very primitive status.