Wetting behavior of iron-nickel-cobalt-copper-oxygen-sulfur melts against olivine and chromite as a function of melt composition, oxygen fugacity, and pressure

The wettability of complex sulfide liquids against solid olivine and chromite was investigated as a function of sulfide liquid composition (Ni, Cu, or Co; 0–30 wt%), oxygen fugacity (10−8–10 −10) and pressure (1 atm; olivine and chromite, 1 and 2 GPa; olivine). Low pressure experiments contained within olivine crucibles were performed at 1300°C in a gas-mixing furnace employing C-O-S gas mixtures to control oxygen and sulfur fugacity. High pressure experiments encapsulated in graphite were performed in a piston-cylinder using Fe₂O ₃ as a buffering agent. The ability of a sulfide liquid to wet a solid olivine (or to a greater extent, chromite) matrix, is controlled by its dissolved oxygen content; present as surface-active metal-oxide. All investigated variables serve to either impede (e.g., addition of Ni, Cu, Co at low $fO2$) or enhance (e.g., addition of Ni, Cu, Co at high $fO2$) the activity of surface-active metal-oxide species within the melt.