Isotope anomalies in primitive meteorites
Final Report Abstract
The project was limited to three months to test the feasibility of the procedure. During this period Sasha Borisov did optimize the metal extraction procedure, including the production of a single metal spherule that could then be easily dissolved in HCl for recovering Mo (details see below). The ICP-MS analyses of Thorsten Kleine showed that the Mo-blank of the procedure is too high for accurately determing the Mo-isotopic composition in ameteorite sample and that starting materials also had too high Mo-contents. The next step was trying to produce metal by in situ reduction. The meteorite samples were put into a furnace at rather reducing conditions. The FeO-would be reduced to metal and a metal bleb would form that could be separated and analyzed in the same way as before except that Mo contamination was excluded. A few experiments were done in the lab of Andreas Pack at the university of Goettingen. Andreas Pack has built furnace with aerodynamic levitation of laser-heated solids in gas stream. The gas stream carries the sample and defines by its composition the oxygen fugacity. An H2-rich gas was employed, metal formed but the formation of a single metal spherule that would contain all Mo was impossible. Whereas metal sphemles form easily in sample where the melting point is reduced by addifion aflux, this is not possible in pur meteoriter sample. The net result of this work was that isolation of Mo and other siderophile elements by the metal extraction method is not very promising, primarily because of the highly blanks involved. In addition, in situ reduction did not work as expected. We therefore gave up attempting to isolate Mo through metal extraction techniques.
