Discovery of metallic residues of the Rochechouart meteorite in basement rocks

The Rochechouart structure of Triassic or early Jurassic age is deeply eroded to the level of the crater floor. At Champonger, the crater floor could be recognized by the association of shatter cones in shocked basement rocks overlain by low temperature suevite. Metal veinlets and particles were found to occur in Champonger basement gneisses within shock produced inter- and intragranular microfractures in various minerals. The metals very probably are condensates of the vaporized impacting projectile and were probably implanted as metal vapor. The condensed metallic vapor was tightly sealed within these fractures. The metals consist of an alloy containing on the average 73 wt. % Fe, 17 wt. % Cr and 8 wt. % Ni. No Mn was found, small amounts of Co may be present. Due to the high Cr content we suggest that the Rochechouart meteorite was a stony and not an iron as previously proposed by Janssens et al. (1977).