Introduction

The three major chondrite classes (carbonaceous, ordinary and enstatite) are supplemented by two additional sets of meteorites: the rumurutiites (R chondrites) and Kakangari (K) chondrites. Other than being primitive chondrites, the R and K meteorites have no generic relationship to each other, but to save on paper, we consider them together in this chapter. The type specimen, and only observed fall, of the R chondrites is Rumuruti. It fell in Rumuruti, Kenya in 1934 [5.1], but was not described until 1994 [5.2]. Not accounting for pairing, as of June 2014, there were 152 rumurutiites, most of which have been recovered from northern Africa [5.3]. Rumuruti chondrites are not subdivided into groups, but are probably from a single body. They exhibit a range of petrologic types, from 3 to 6 (Figure 5.1), implying that the parent body has been subject to thermal modification. It has been argued that R chondrites may be part of an OC “super-clan” [5.4], but this interpretation has been rejected in favour of designating the meteorites as a separate class [5.2, 5.5].

Three K-type chondrites are currently (June 2014) listed in the Meteoritical Bulletin [5.3]. The type specimen, Kakangari, fell in Tamil Nadu State, India in 1890 [5.1]. Kakangari has had a varied classification history, first as a unique chondrite, designated a K chondrite [5.6, 5.7], a forsterite chondrite [5.8] then associated with Adelaide and Bench Crater as a CK (for Kakangari) chondrite [5.9]. Since 1989, however, Kakangari has been regarded as belonging to no known chondrite group [5.10], and now forms its own grouplet [5.11] along with Lewis Cliff 87232 (originally classified as a possible CR2 [5.3]) and Lea County 002 [5.12]. This last was originally classified as an anomalous chondrite [5.3], then thought to be a K chondrite [5.11]. There are, however, sufficient differences between Lea County 002 and Kakangari/LEW 87232 for its classification to be questioned, and it might be a weathered CR2 chondrite [5.13]. Because of this doubt, Lea County 002 will be excluded from further consideration. Kakangari and LEW 87232 are both petrologic type 3.

Much of the information in this chapter about R chondrites is drawn from the review paper by Bischoff et al. (2011) [5.14]; similarly, information about K chondrites comes mainly from Weisberg et al. (1996) [5.11].