Mineralogy versus bulk composition of the carbonaceous chondrite clast Kaidun 2

Kaidun is an unusual chondritic meteorite. Its main mass is of CR-type (Kaidun I) and contains CI-like (Kaidun II), EL, and EH clasts. The classification of Kaidun II based on mineralogy and bulk chemical criteria does not allow an unambigious assignment to CI. Here we report on the bulk chemical composition and the mineralogy of the Kaidun II clasts. The results of our investigation show that Kaidun II has some characteristics of both CI and CM chondrites. A possible relationship to the texture and composition of micrometeorites is indicated. The Kaidun II clast shows some conflicting mineralogical and chemical characteristics that do not allow an unambigious assignment to the well established carbonaceous chondrite classes. The overall texture of the matrix-rich clast and morphology of opaques are typical for CI's. Bulk matrix and bulk sample compositions reveal similarities with CM's. In addition, the presence of low-Fe Mn-enriched olivines and the relatively high abundance of enstatite resembles some micrometeorites.