Other, less common chondrite groups provide important insight into our early solar system history, as well as details on chondrite formation. In our carbonaceous chondrite section we explained how specific groups formed under variable oxidizing conditions based upon their distance from the Sun. For example, the CI and CM chondrite groups formed under the more oxidizing conditions present in the outer regions of the solar nebula. In contrast, groups such as the CO and CH chondrites formed under more reducing conditions, indicative of a closer proximity to the Sun. The same holds true for the other chondrite groups and they can be placed into a continuous sequence along with the ordinary chondrites.
On one extreme, we find the highly reduced enstatite, or E chondrites that must have formed more closely to the Sun than the H, L, or LL chondrites. At the other extreme, we find the highly oxidized rumurutiites, or R chondrites that attest to a formation further from the Sun. We will elaborate on both groups in the respective sections.
Finally, we'd like to introduce two other groups or grouplets of chondrites that don't easily fit into existing schemes. The kakangariites, or K chondrites consist of only three members, while the forsterite, or F chondrites are a more hypothetical grouplet. Its "members" are merely inclusions that have been found as xenoliths inside certain brecciated achondrites.