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Abatract-F'reviously, three meteorites from Australia and Antarctica were described as a new chondritic "grouplet" ( Acfer 217 is a regolith breccia consistimg of up to cm-sized clasts (=33 ~01%) embedded in a fme-grained, well-limed clastic matrix. The most abundant mineral is olivine (a72 vol%), which has a high Facontent of 37-39 mol%. The major minerals (olivine, Iow-Ca pyroxene, Ca-pyroxene, and plagioclase) show some compositional variability indicating a slightly unequilibrated nature of the meteorite.Considering the mean olivine composition Of Fa37.8 * 5.7, a classification of M e r 217 as a R3.8 chondrite would result; however, Acfer 217 is a regolith breccia consisting of clasts of various petrologic types. Therefore, we suggest to classify Acfer 217 as a R3-5 chondrite regolith breccia. The bulk meteorite is very weakly shocked (S2).The bulk composition of Acfer 217 and other R-meteorites show that the R-meteorites are basically chondritic in composition. The pattern of moderately volatile elements is unique in R chon&, Na and Mn are essentially undepleted, similar to ordinary chondrites, while Zn and Se contents are similar to concentrations in CM chondrites. The oxygen isotopic composition in Acfer 217 is similar to that of Rumwuti, Carlisle Lakes, AL.H 85 15 1, and Y-75302. In a 6 170 vs. 61 8O-diagram, the R-meteorites form a group well resolved h m other chondrite groups.Acfer 2 17 was a meteoroid of common size with a radius between 15 -65 cm and with a single stage exposure history. Based on 21Ne, an exposure age of about 35 Ma was calculated.

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