Elemental Composition and Optical Properties of Cometary Dust Particles in the Coma of Comet 67P

<p>The COmetary Secondary Ion Mass Analyser (COSIMA) instrument on board ESA's Rosetta mission to comet 67P/Churyumov&#8211;Gerasimenko has collected and analysed dust particles in the inner coma from August 2014 to September 2016 between 1.25 and 3.8 AU solar distance and 4 to 1000 km off the comet nucleus. The dust particles were identified with optical microscopy and analysed with secondary ion mass spectrometry (SIMS). The elemental composition of the dust particles collected and analysed with SIMS is heterogeneous for the mineral forming elements within a factor of 2. The potential relation between optical properties and dust particle elemental ratio of carbon and silicon has been studied.&#160;</p>