Transport and concentration of molybdenum in granite molybdenite systems: Effects of fluorine and sulfur

To investigate the effects of F and S on the transport and concentration of Mo in granite molybdenite deposits, we prepared four synthetic granite compositions with Mo, S, and F. Each composition was run at 1000 °C and 100 MPa with 6 wt % H₂O to stabilize the phase assemblage liquid + aqueous vapor. In all compositions, Mo is partitioned into the vapor phase and deposited on the capsule walls, in vapor bubbles in the quenched glasses, or in silica-rich spherules. F and S do not affect the partitioning of Mo. However, S plays a critical role in the deposition of Mo from the vapor phase. Thus, the initial water content of the magma, which controls the timing of vapor phase evolution, and the presence of S are primary controls on Mo ore deposition in these deposits.