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Fluid inclusions coexisting with the silicate melt inclusions are metal-rich but predate sulphide precipitation and were therefore not responsible for the Cu-Au mineralisation at the Late Cretaceous Elatsite porphyry deposit. Bornite, chalcopyrite and magnetite seem to have been precipitated slightly later at 460 degrees C in separate veins or opened spaces of preexisting veins. The next, economically most important chalcopyrite-pyrite stage was largely devoid of quartz precipitation and is mostly expressed as paint veins, a thin sulphide veneer on often numerous planar fractures. Due to the lack of fluid inclusions, the temperature-pressure conditions of formation of these veins cannot be constrained. Laser ablation-inductively coupled plasma-mass spectrometry analysis of fluid inclusions shows very high Cu contents in early intermediate-density fluid inclusions and in the first vapour inclusion generation, followed by a drastic decrease in the second generation of vapour inclusions. A progressive Cu enrichment in the brine phase correlates well with depressurisation prior to mineralisation. Mass balance considerations based on analysed fluid components and fluid phase relations indicate that brine was volumetrically minor and therefore likely to have been stagnant, but this may have prepared ore precipitation by accumulating Cu stripped from ascending vapour., Fluid inclusions coexisting with the silicate melt inclusions are metal-rich but predate sulphide precipitation and were therefore not responsible for the Cu-Au mineralisation at the Late Cretaceous Elatsite porphyry deposit. Bornite, chalcopyrite and magnetite seem to have been precipitated slightly later at 460 degrees C in separate veins or opened spaces of preexisting veins. The next, economically most important chalcopyrite-pyrite stage was largely devoid of quartz precipitation and is mostly expressed as paint veins, a thin sulphide veneer on often numerous planar fractures. Due to the lack of fluid inclusions, the temperature-pressure conditions of formation of these veins cannot be constrained. Laser ablation-inductively coupled plasma-mass spectrometry analysis of fluid inclusions shows very high Cu contents in early intermediate-density fluid inclusions and in the first vapour inclusion generation, followed by a drastic decrease in the second generation of vapour inclusions. A progressive Cu enrichment in the brine phase correlates well with depressurisation prior to mineralisation. Mass balance considerations based on analysed fluid components and fluid phase relations indicate that brine was volumetrically minor and therefore likely to have been stagnant, but this may have prepared ore precipitation by accumulating Cu stripped from ascending vapour.