title: Carbon abundance and silicate mineralogy of anhydrous interplanetary dust particles.
abstract: We have studied nineteen anhydrous chondritic interplanetary dust particles (IDPs) using analytical electron microscopy.  We have determined a method for quantitative light element EDX analysis of small particles and have applied these techniques to a group of IDPs.  Our results show that some IDPs have significantly higher bulk carbon abundances than do carbonaceous chondrites.  We have also identified a relationship between carbon abundance and silicate mineralogy in our set of anhydrous IDPs.  In general, these particles are dominated by pyroxene, olivine, or a subequal mixture of olivine and pyroxene.  The pyroxene-dominated IDPs have a higher carbon abundance than those dominated by olivines.  Members of the mixed mineralogy IDPs can be grouped with either the pyroxene- or olivine-dominated particles based on their carbon abundance.  The high carbon, pyroxene-dominated particles have primitive mineralogies and bulk compositions which show strong similarities to cometary dust particles.  We believe that the lower carbon, olivine-dominated IDPs are probably derived from asteroids.  Based on carbon abundances, the mixed-mineralogy group represents particles derived from either comets or asteroids.  We believe that the high carbon, pyroxene-rich anhydrous IDPs are the best candidates for cometary dust.
authors.affiliation: Lockheed Engineering and Science Co., Houston, TX 77058, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Thomas
authors.forename: G E
authors.initials: GE
authors.lastname: Blanford
authors.forename: L P
authors.initials: LP
authors.lastname: Keller
authors.forename: W
authors.initials: W
authors.lastname: Klock
authors.forename: D S
authors.initials: DS
authors.lastname: McKay
mesh_terms: D001256:Astronomy / Q000379:methods; D002244:Carbon / Q000737:chemistry*; D019443:Cosmic Dust / Q000032:analysis*; D005118:Extraterrestrial Environment; D058085:Iron Compounds / Q000737:chemistry; D017616:Magnesium Compounds / Q000737:chemistry; D019110:Meteoroids; D008854:Microscopy, Electron; D008903:Minerals / Q000737:chemistry*; D018543:Minor Planets; D017640:Silicates / Q000737:chemistry*; D012984:Software
chemical_list: D019443:Cosmic Dust; D058085:Iron Compounds; D017616:Magnesium Compounds; D008903:Minerals; D017640:Silicates; C092478:pyroxene; D002244:Carbon; C034475:olivine