Comparing Wild 2 particles to chondrites and IDPs

Michael Zolensky, Keiko Nakamura-Messenger, Frans Rietmeijer, Hugues Leroux, Takashi Mikouchi, Kazumasa Ohsumi, Steven Simon, Lawrence Grossman, Thomas Stephan, Michael Weisberg, Michael Velbel, Thomas Zega, Rhonda Stroud, Kazushige Tomeoka, Ichiro Ohnishi, Naotaka Tomioka, Tomoki Nakamura, Graciela Matrajt, David Joswiak, Donald BrownleeFalko Langenhorst, Alexander Krot, Anton Kearsley, Hope Ishii, Giles Graham, Zu Rong Dai, Miaofang Chi, John Bradley, Kenji Hagiya, Matthieu Gounelle, Lindsay Keller, John Bridges

Research output: Contribution to journalArticlepeer-review

137 Scopus citations


We compare the observed composition ranges of olivine, pyroxene, and Fe-Ni sulfides in Wild 2 grains with those from chondritic interplanetary dust particles (IDPs) and chondrite classes to explore whether these data suggest affinities to known hydrous materials in particular. Wild 2 olivine has an extremely wide composition range, from Fa0-96, with a pronounced frequency peak at Fa1. The composition range displayed by the low-calcium pyroxene is also very extensive, from Fs48 to Fs0, with a significant frequency peak centered at Fs5. These ranges are as broad or broader than those reported for any other extraterrestrial material. Wild 2 Fe-Ni sulfides mainly have compositions close to that of FeS, with less than 2 atom% Ni; to date, only two pentlandite grains have been found among the Wild grains, suggesting that this mineral is not abundant. The complete lack of compositions between FeS and pentlandite (with intermediate solid solution compositions) suggests (but does not require) that FeS and pentlandite condensed as crystalline species, i.e., did not form as amorphous phases, which later became annealed. While we have not yet observed any direct evidence of water-bearing minerals, the presence of Ni-bearing sulfides, and magnesium-dominated olivine and low-Ca pyroxene does not rule out their presence at low abundance. We do conclude that new investigations of major- and minor- element compositions of chondrite matrix and IDPs are required.

Original languageEnglish (US)
Pages (from-to)261-272
Number of pages12
JournalMeteoritics and Planetary Science
Issue number1-2
StatePublished - 2008

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science


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