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Dingwell, Donald B. (1991): Redox viscometry of some Fe-bearing silicate melts. In: American Mineralogist, Vol. 76, Nr. 9-10: S. 1560-1562




The dependence of shear viscosity on the oxidation state of six ferrosilicate melts has been measured using the concentric cylinder method and a gas mixing furnace. The measurements were performed under air, COr, and COr-CO mixtures at I atm and in a temperature range of 1345 to 1470"C. The experimental procedure involved a continuous measurement of viscosity during stepwise reduction of the melts. Melt chemistry was controlled by dip sampling the tiquids at each oxidation state. The resulting glassesw ere analyzed by electron microprobe, a volumetric FeO itration, and 57Fe Mdssbauer spectroscopy. The electron microprobe data indicate Fe loss for some of the most reduced samples.T he wet chemical (+ microprobe) and spectroscopicd eterminations of theseF erich samples yield oxidation states that are in excellent agreement. The viscosity of all melts investigated herein decreasesw ith melt reduction. The viscosity decrease is, in general, a nonlinear function of oxidation state expressed as Fe2*/F€,o,.