Member of a rare group of chondrites, formerly named the Carlisle Lakes group, after a meteorite found in Australia in 1977. It is now named for the type specimen Rumuruti that fell in Kenya, Africa, in 1934. Rumuruti is the only
witnessed fall of this group and only one small individual has been preserved in the collection of the Humboldt Museum Berlin, Germany, since 1938. Rumuruti was considered an anomalous chondrite until it was reclassified in 1993 and the R group was formed. The R chondrites are quite different from ordinary chondrites and are opposite the E chondrites when it comes to mineralogy and oxidation state. R chondrites are highly oxidized, containing high amounts of Fe-rich olivine. They contain almost no free metal (most of the Fe is either oxidized in silicates) or in the form of Fe sulfides. The Fe-rich olivine and oxidized nature of the Fe, give most R chondrites a typical red appearance. The meteorites of this group contain fewer chondrules than do ordinary or E
chondrites, but they often contain xenoliths that are samples of asteroid regolith. Another indicator for a regolith origin is that most R group meteorites contain high concentrations of noble gases implanted by the solar wind. The parent body of the R chondrites has yet to be found, but must have undergone many impact events during its history to yield the high degree of brecciation shown by most R group members.

NWA 2069. Image © T. E. Bunch 2004

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