Mineralogical studies of Silicate stardust in the laboratory A. N Mineralogical studies of Silicate stardust in the laboratory A. N. Nguyen1,2, L. P. Keller1, S. Messenger1, K. Nakamura-Messenger1, and Z. Rahman1,2 1Robert M. Walker Laboratory for Space Science, ARES, NASA JSC, 2Jacobs Technology, Houston TX, USA (lan-anh.n.nguyen@nasa.gov) Laboratory analyses of the mineral and chemical properties of silicate stardust grains mostly agree with astronomical observations Majority of grains are Fe-bearing amorphous silicates with non-stoichiometric compositions Crystalline silicates make up ~1/3 of analyzed grains. This abundance is much greater than the fraction observed in the ISM (< 1%) Suggests recrystallization of amorphized grains or preferential destruction of amorphous silicates Olivine grains have higher Fe-contents than pyroxene grains Amorphization in space is rare Two amorphized grains have been observed Laboratory analyses of silicate stardust unveil details that cannot be observed remotely Many grains (~20%) are aggregates of amorphous and crystalline silicate phases, or compound silicate and oxide grains Some grains have FeNi metal inclusions Mg Si Fe Pyroxene Olivine