The experiments on the simultaneous partitioning of divalent cations (Ni2+, Mg2+, Co2+, Zn2+, Fe2+, and Mn2+) between pyrite or pyrrhotite and 2M aqueous chloride solution were conducted under supercritical hydrothermal conditions of 500, 600, 700, and 800 °C, and 1 kb, using standard cold seal type pressure vessels.
The experimental results revealed that the cations are preferentially partitioned into pyrite and pyrrhotite in the following orders, respectively:
Co2+=Ni2+=Fe2+>Zn2+>Mg2+=Mn2+ for pyrite
and
Co2+>Ni2+≥Fe2+>Zn2+>Mg2+=Mn2+ for pyrrhotite.
If we assume that Mg2+ shows a partition behavior according to the ionic radius, the partition coefficient vs. ionic radius (PC-IR) curves for both pyrite and pyrrhotite mark a peak at 0.77 Å. Zn2+ shows a negative deviation from the PC-IR curves, but Ni2+ shows a positive deviation.