Figure 1

Approximate log –pH conditions of Mississippi Valley-type (MVT) and red-bed related base metal (RBRBM) model ore fluids at 100°C (regions bounded by heavy lines). The stability fields of Cu–Fe–S–O minerals constructed for total sulfur of 10^-2 mol kg^-1 and aqueous sulfur species are deliniated by the light and medium boundaries, respectively. Abbreviations: Bn = bornite; Cp = chalcopyrite; Hem = hematite: Mt = magnetite; Po = pyrrhotite; Py = pyrite. Neutral pH is indicated by the vertical arrow.