Post-doc ORIGINS Fellow, April – October 2010, Natural History Museum, London (UK) I had the chance of obtaining a post-doc ORIGINS fellowship at the Natural history Museum in London (UK) just after the conclusion of my PhD. I obtained my PhD at the Department of Physics and Astronomy of the University of Florence (Italy), where I worked under the direction of Santi Aiello and Emanuele Pace. The field of my PhD thesis was that of meteoritics or, in other words, the study of extraterrestrial material. The principal subject of my work was the search for and the characterization of small inclusions in meteorites. Such small inclusions are characterized by an origin different from that of their host meteorites. For this reason they are called xenoliths. In particular I focused my attention on carbonaceous microxenoliths, that is xenoliths with sizes smaller than 1 mm and with properties similar to those of carbonaceous chondrites (Fig. 1). Carbonaceous microxenoliths are samples of the most abundant particles that populate the inner Solar System, forming the so-called zodiacal cloud. The unique property of microxenoliths is that they are samples of ancient epochs, because they can have been embedded in their host meteorites hundreds of millions of years ago. Even if carbonaceous microxenoliths present strong similarities with micrometeorites (millimetric and sub-millimetric extraterrestrial samples mostly collected in the Antarctic ice and snow), the latter were part of the zodiacal cloud in more recent times than microxenoliths. This, in addition to the fact that it is possible to find microxenoliths that did not suffer important alterations by water or by high temperatures, make microxenoliths a very important class of extraterrestrial objects to study the origin and the evolution of the Solar System. Fig. 1. A back-scattered electron image of a carbonaceous microxenolith in the ordinary chondrite Plainview 1917. The white line highlights the microxenolith edges. During my Phd I realized different experimental works in order to characterize microxenoliths. Their mineralogy has been studied by scanning electron microscopy and electron microprobe analysis, and selected microxenoliths have also been studied by transmission electron microscopy. Multi-wave Raman spectroscopy analyses have been performed to characterize the organic matter present in the microxenoliths. Secondary ion mass spectrometry has been performed to investigate the isotopic composition of hydrogen, carbon and nitrogen of a few microxenoliths. Part of these works has been realized thanks to the collaboration I started with Matthieu Gounelle, of the Laboratoire de Minéralogie et Cosmochimie du Muséum of the National Natural History Museum of Paris (France). The experimental techniques I learned during my PhD have been the basis of the work that I developed during the period of my ORIGINS fellowship. For this work I focused my attention on CR chondrites, a group of carbonaceous chondrites considered among the most pristine in our collection of meteorites. The goal of my work was to find effects of low degree metamorphic processes, to verify whether these meteorites really escaped any thermal alteration or if they suffered moderately high temperatures. To realize this goal, I analyzed the structure and the chemical composition of metal grains in CR chondrites by scanning electron microscopy and electron microprobe analysis. Also I performed Raman spectroscopy analyses on the CR chondrites organic matter. Both these techniques allow investigating the thermal history of the samples. Indeed, for at least two meteorites, I observed evidences of thermal metamorphism. The ORIGINS fellowship gave me unique possibilities to realize this work. Beside the possibility of using state-of-the-art experimental facilities, as the scanning electron microscope and the electron microprobe of the Natural History Museum in London, the context of the ORIGINS network gave me the chance of visiting different European laboratories and meeting some of the most important European scientists in the field of meteoritics and cosmochemistry. I really appreciated this aspect of international cooperation and exchange, and I think this has been a really fruitful experience for the career I want to pursue in the field of academic research.