Rietmeijer (TEM): Particle contains extremely rare pyrrhotite, extremely raregrains that are a regular mixture (crystallographic controlled intergrowth?) of pyrrhotite and kamacite, round kamacite inclusions in the aerogel, (Fe,Ni,Cr)3Si spheres (seussite) scattered in aerogel, and single crystal forsterite. He provides many analyses of sulfides,olivine, seussite, Fe-Ni metal and Si-rich glass. He is confident that the Fe-silicide (seussite) spheres are the reaction product between iron from comet material and aerogel.If so, the Fe-Si phase diagram would suggest peak-heating temperatures at least on the order of 1200-1400 oC. The amorphous zone betwen forsterite and aerogel does notrepresent an “inert compressed aerogel”. It suggests chemical exchange between thecomet dust and the aerogel capture medium. The process is unclear: it could be a meltzone or due to solid-state diffusion at very high chemical diffusion rates.
| Notes By: | ndc\cpgonzal | Date: | 06/04/2010 |