A) Phase abundances as predicted by rhyolite-MELTS 1.1.x (Gualda & Ghiorso, 2015). Phase abundance here is in terms of mass. B) Bulk partition coefficient, D, for Sr and Rb as a function of crystallinity. Simulations performed at 200 MPa, ca. 5 wt % H2O, a starting composition listed in Table 2, and QFM+1 for the oxygen buffer. Note eutectic is reached at ca. 20 % crystallization.