A ton of Re oxides should always be worth more than a ton of Re carbonate
It is to do with the Atomic mass of each element
as an example
Lanthanum = 138.90547
Carbon = 12.011
Oxygen = 15.999
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Lanthanum carbonate, La2(CO3)3 = 457.838
Lanthanum oxide is La2O3 = 325.809
2 Lanthanum atoms = 277.81094
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You can see how the oxide adds to the molecular mass and how much more the carbonate adds
Typically if you convert an Re oxide to a metal you lose at least 15% of the mass and even more so when you convert the carbonate .
It appears that the (CO3)3 is about 39% and the O3 about 15%
which means that in a tonne of lanthanum carbonate ,there is only approx 610kg of Lanthanum and in a tonne of Lanthanum Oxide the is about 850 Kg of lanthanum
Hope that helps but I am sure that other posters could explain it better and provide a better example
Tonio
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