9418719 Seyfried This research will utilize a newly developed method to measure near equilibrium dissolution and precipitation rates of minerals in the CaO-MgO-SiO2-H2O system at temperatures from 100-400 oC and pressures up to 1 kbar. The method involves measuring rates of crystal growth and dissolution during reaction of fluids with metastable reactant and stable product minerals. The technique to be used involves monitoring reaction progress continuously during experiments by means of isotopic tracers. Metastable steady state conditions and adjustments of the relative states of saturation with respect to mineral phases can be established by systematically changing the relative surface areas of "reactant" and "product". Results of the experiments will provide near-equilibrium rate data for geochemically important minerals at a wide range of temperatures and pressures. These data can be included in reaction path codes such as EQ6, which will allow construction of better models for the chemical evolution of fluids in active hydrothermal systems.
