Cellular Precipitates of Iron Oxide in Olivine in a Stratospheric Interplanetary Dust Particle

Frans J. M. Rietmeijer
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, USA

Abstract: The petrology of a massive olivine-sulphide interplanetary dust particle shows melting of Fe,Ni-sulphide plus complete loss of sulphur and subsequent quenching to a mixture of iron-oxides and Fe,Ni-metal. Oxidation of the fayalite component in olivine produced maghemite discs and cellular intergrowths with olivine and rare andradite-rich garnet. Cellular reactions require no long-range solid-state diffusion and are kinetically favourable during pyrometamorphic oxidation. Local melting of the cellular intergrowths resulted in three dimensional symplectic textures. Dynamic pyrometamorphism of this asteroidal particle occurred at ∼1100°C during atmospheric entry flash (5–15 s) heating.

Keywords: olivine • cellular precipitates • iron oxide • interplanetary dust

Mineralogical Magazine; December 1996 v. 60; no. 403; p. 877-885; DOI: 10.1180/minmag.1996.060.403.03
© 1996, The Mineralogical Society
Mineralogical Society (www.minersoc.org)