Experiments will be conducted to determine oxygen and hydrogen isotope fractionation between alunite and water over the temperature range of 250 to 450oC. Exchange experiments will be conducted in cold seal hydrothermal vessels with runs of 1 to 3 months duration, and will involve coupling of isotope exchange with Na-K exchange to facilitate attainment of equilibrium. Knowledge of alunite fractionation factors will allow calibration of alunite-quartz and alunite-pyrite isotope geothermometers, and will permit interpretaion of alunite-bearing deposits in terms of temperatures of formation and the chemical compositions of the various fluids that produced them.
