Chiara M. Domeneghetti
I am a mineralogist and my field of interest developed in the crystal-chemistry of rock-forming minerals, mainly pyroxenes. In particular I studied, by single-crystal X-ray diffraction the structural variations which occur in pyroxenes and amphiboles as a function of chemical composition and degree of order. The aim was that of investigating how in these minerals the cation distribution affects geometrical parameters of the structure and of finding their correlations with the formation conditions. M.C.D. studied both thermodynamic and kinetic aspects of order-disorder reactions in pyroxenes under controlled conditions of T and pO2 and phase transitions in pigeonite and cummingtonite induced by in situ annealings. In particular M.C.D.: a) investigated the convergent ordering process in omphacites, applying the Landau theory to the results of X-ray diffraction and using IR spectroscopy to analyse local heterogeneities; b) studied the non convergent ordering in orthopyroxene and pigeonite using the Mueller-Ganguly approach. This allowed her to obtain information about the cooling rate of host rocks and also to constrain the thermal history of meteorite and lunar samples. More recently M.C.D focused on the study of thermal expansion and compressibility of minerals and on the effect, on these properties of the isomorphous substitutions and cation ordering.