Schröcke, H.; Trumm, A.; Hochleitner, Rupert
Uber den Transport von Wolfram und den Absatz von Wolfram- Doppeloxiden in fluiden waSS rigen Losungen.
In: Fortschritte der Mineralogie, Vol. 60, No. 2: pp. 187-213
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Thermodynamic data indicate that W may be transported in the aqueous gas phase above 500oC as fluoride or oxyfluoride, but hardly as hydroxide and that the deposition of wolframite is favoured by decreasing T and P. Eh-pH diagrams and exchange reactions of wolframite with oxides, sulphides and other ions in solution indicate that Fe2WO6 is stable with respect to Fe2O3 + WO3 above 126oC, but at 300oC it is stable only at high PO2 - which are not obtained in endogenous hydrothermal solutions. MgWO4 and BaWO4 have low Gibbs free energies similar to Fe2WO6 and should form minerals if Mg and Ba are present in solution with W.-A.C.B.