(a) log(K/Rb) versus log(Cs) relationship in muscovite composing granite, greisen and the mineralized veins of Panasqueira. (b) Modelled compositional evolution trend of muscovite formed during fractional crystallization of the Panasqueira granite (F gives the fraction of remaining liquid). This trend is calculated applying the Rayleigh equation CiMs=kd,iMs/melt*C0,iLiq*F(Di−1) (Hulsbosch et al., 2014) and assuming a starting composition of granitic melt (C0,iLiq) of 370 ppm Rb, 70 ppm Cs and 44 900 ppm K. Modal proportion of minerals (xj) composing the Panasqueira two-mica granite and mineral/melt partition coefficients (kd,ij) for K, Rb and Cs used for calculation of distribution coefficients (Di) are summarized in table below diagram b. References for kd: aIcenhower and London (1996); bIcenhower and London (1995); cPhilpotts and Schnetzler (1970); dJolliff et al. (1992); eNash and Crecraft (1985).