Dear all,
first I want to thank for the helpful suggestions I got from Pedro Jugo
and Chris Stanley with respect to appropriate standards for analysing
wolframite, particularly the Fe.
We have now tested all these possibilities and finally managed to get good
analytical totals and a very good stoichiometry. Neither of the suggested
standards worked perfectly under our analytical conditions (30 kV, 30 nA),
although the pyrrhotite standard gave slightly too high totals with fairly
good stoichiometry. To our surprise, the best standard turned out to be
the CANMET pentlandite. There might be also a relation to the composition
of the respective wolframite - the ones we have analysed have
approximately Fe90Hu10. In other cases different standards might be more
appropriate.
Best wishes
Thomas Wagner
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