This project will continue detailed studies of the Stillwater Intrusive Complex with the goal of understanding the high tempera- ture hydromagmatic environment and its role in remobilizing trace element components (esp. platinum-group elements, or PGEs) and altering the primary cumulate rocks of the complex. Models of magmatic vs. hydrothermal fluid transport of PGEs) will be tested using (a) compositional variations of hydrous phases (e.g. apatite) as a function of stratigraphic height and in veins vs. cumulate rocks, (b) mass balance of trace element budgets, (c) stable isotope evidence for origin of fluids, (d) phase equilibria constraints on intensive parameters, and (e) preliminary experimental investigations of mineral solubilities in Cl-brines at high temperature.