Conceptual model of greisen formation during the magmatic-hydrothermal transition of Panasqueira. In this model are displayed (a) the schematic time evolution of fluid flow during the granite crystallization and cooling, (b) the textural and the mineralogical evolution of granite with the behavior of some elements considered in this study, (c) zoom on mineralized veins related to QTS and MOSS and (d) log(aNa+/aH+)vs.log(aK+/aH+) phases diagram at 1 kbar illustrating effect of temperatures (from 600 to 400 °C) on equilibria between K-feldspar, albite and muscovite. Triple point corresponds to hypothetic eutectic of the two-mica granite of Panasqueira. During granite cooling, fluid produced at high magmatic temperature (red star) is imbalance with the cooler crystallized part of the granite intrusion that potentially trigger greisenization. This diagram was built from thermodynamic database of SUPCRTBL (Johnson et al., 1992; Zimmer et al., 2016).