Occurrence and possible significance of rare Ti oxides (Magnéli phases) in carbonaceous chondrite matrices

Rare, ultrafine‐grained Ti oxides (Ti 3 O 5 and the Magnéli phases, Ti 5 O 9 and Ti 8 O 15 ) have been identified by transmission electron microscopy in the CM2 carbonaceous chondrite, Bells and a carbonaceous chondrite matrix clast from the Nilpena polymict ureilite. In both meteorites the Ti oxides occur in the matrix as isolated grains and clusters of two or more grains. They are euhedral in shape and have grain sizes of 0.05–0.3 μm. Magnéli phases have been recently shown to be a common component in some interplanetary dust particles, but this is the first reported occurrence in a meteorite. The morphological properties and grain size of the Ti oxides are consistent with formation by vapor phase condensation either within the solar nebula or possibly in a presolar environment.