Hochleitner, Rupert; Schröcke, H.
Heterogeneous equilibria in the Wolframite group [Heterogene Gleichgewichte in der Wolframitgruppe].
In: TMPM Tschermaks Mineralogische und Petrographische Mitteilungen, Vol. 34, No. 1: pp. 35-47
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In the system Fe-Mn-W-O solid state equilibria at 1000°C were determined beginning with all binary and ternary bordering systems. In the system Fe-Mn-W the ternary phase Mn5Fe2.7W2.3 was found. In the system Fe-Mn-O there does not exist any ternary phase. In the other systems only FeWO4, Fe2WO6 and MnWO4 exist. Mn4WO6 could not be synthesized up to 100 atm partial pressure of oxygen. Quaternary phases do not exist. ZnWO4 and NiWO4 are not stable in coexistence with FeO and MnO oxides. Reaction products are always FeWO4 or MnWO4 with ZnO or NiO. Hydrothermal studies at pH2O=2000 atm showed complete solid solution in the system FeWO4-MnWO4 down to 160°C. Schröcke (1960) found an asymmetrical miscibility gap in the system FeWO4-NiWO4 by means of solid state reactions. Now this miscibility gap has been corrected: Critical temperature 525°C, critical composition 0,15 FeWO4. Complete miscibility exists in the systems FeWO4-ZnWO4 and MnWO4-ZnWO4 down to at least 414°C, in the system MnWO4-NiWO4 down to at least 454°C.