Metal-rich slurries discharged from excess-enthalpy geothermal wells at Kawerau (NZ) indicate that an efficient ore
precipitation mechanism operates in some feedzones. In our conceptual model, which takes into account the relative
permeabilities of liquid and gas phases in boiling fluids, a metal-precipitating liquid phase is effectively immobilised along
boiling fronts, leading to the formation of highly concentrated ore. Chemical equilibrium and heat/mass transport modeling
demonstrate the general applicability of this conceptual model to hydrothermal eruption environments.