Kaidun meteorite: Crystals of oxides in cavities

Cavities in two texturally and genetically distinct clasts of the Kaidun meteorite were found out to contain crystals of distinct morphology, but of a similar composition. Cavities in chondrite breccia #d3A contain thin (< 4 mu m) elongated ( up to 25 mu m long) crystals that grew perpendicular to the walls of the cavity. The walls of the cavities in partly fused clast #d( 3- 5) D are covered with clusters of acicular crystals. In both clasts, the crystals are covered by films of phyllosilicates and always have a composition approximated by the formula (Mg, Fe, Mn)(5)Al2O8 center dot n H2O. No mineral phase of this composition has ever been found in nature. The genesis of the mineral phases in the cavities is thought to be related to the crystallization from a fluid of similar composition. The fluid was produced during the cooling of the melt that produced clast # d( 3- 5) D. The unusual composition of the crystals testifies that this fluid had an unusual composition. This can be explained by the unique nature of clast # d( 3- 5) D, for which there are good reasons to propose a Martian origin.