The are two molybdenite polytypes; a hexagonal (2H) and the more rare rhombohedral (3R). The purpose of this study is to determine which molybdenite polytype is most likely to remain closed to Re-Os exchange after deposition. The PI proposes to obtain molybdenites from different types of ore-deposits of known age, and determine the polytype by XRD analysis and analyze the Re-Os abundances by isotope dilution using an ICP-MS. The second purpose of this work is to determine the Re-Os isotope systematics of sulfides from porphyry copper/molybdenum deposits from Arizona, New Mexico, northern Mexico, Nevada and Utah in order to constrain the crust/mantle input of metals into these systems.
