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 will include microscopic examination of thin sections with transmitted and reflected lights, detailed description of mineralogy and texture, classification of rocks where possible, visually estimated modal proportion of minerals, and description of primary and secondary minerals and their paragenetic sequence. In mineralized samples, the genesis of ore will be estimated. All reports will include 2 or more photomicrographs of each thin section taken by a digital Leica cooled camera, a cd with file(s) and 2 hard copies of the report.