Schematic diagram of trace element box model developed in this study for the case of melt loss. Four reservoirs exist: mass of melt, MM, mass of melt lost, ML, mass of crystallized solid, MC, and mass of crystal lost, MCL. MCL is not shown in the illustration but is similar to ML except that it takes mass away from the solid. Simulations take into account either no mass loss or either (not both) melt or crystal loss. The sum of mass in all reservoirs is constant M0, the initial mass of melt. Each reservoir has an associated concentration of the trace element of interest which is solved for using eqs. 1-4. Here, S is mass of trace element of interest, M is mass of reservoir, and C is concentration of trace element. In the case of melt loss, the sample is comprised of only retained melt (melt reservoir) and accumulated crystals (crystal reservoir).