Porphyry-hosted molybdenum deposits are divided into low and high fluorine types. The low fluorine-type deposits are related to porphyry-copper deposits and are associated with continental volcanic arcs (cf. Ludington et al. 2009-2011). Some examples are the Red Mountain in Yukon, Thompson Creek in Idaho, and the Boss Mountain and Kitsault deposits in British Columbia. Their alteration zone is comparable to porphyry-style deposits, having a potassic (and silicic) core, surrounded by phyllic and distal propylitic alteration.
High fluorine type – or Climax-type deposits occur in extensional environments and are associated with A-type calc-alkaline granites (Lundington et al., 2009-2015). The rocks are highly evolved and in addition to molybdenum they often contain high concentrations of rare earth elements, tantalum, niobium and uranium. Their alteration zone consists of a potassium-rich core with quartz-molybdenite veins and the deposit is overlain by a sericite-rich zone. The propylitic zone generally extends well into the country rocks (Lundington et al., 2009-2015).
Petrographic Reports on Molybdenum (MOLY) deposits will concentrate on the identification of accessory minerals, the type of alteration and the identification of rock types. All of the above are essential in identifying the deposit type, as well as the proximity to the ore. Petrographic studies on molybdenum deposits by GeoConsult includes a series of reports on the Kitsault mine in British Columbia, Canada (for Avanti Mining).
Detailed information on Petrographic Reports is provided in GeoConsult Services.
(x-axis of photos: 1.6mm)