aThe composition of this model ore fluid is a composite based on parameter values proposed by Rose,[23,24] Sverjensky,[31,32] and Branam and Ripley. bChlorinity = Cl- concentration in mg L-1. Calculated from and assuming a fluid density of l.l g cm-3cSalinity = total dissolved solids (TDS) in mg L-1. Calculated assuming a fluid density of l.l g cm-3. dPyrite stability field only. eHematite stability field only. fMagnetite stability field only.