Feasibility Study and Technical Report - Pretivm

Vein mineralization includes trace to 10% combined disseminated pyrite, tetrahedrite,tennantite, arsenopyrite, chalcopyrite, galena, sphalerite, pyrargyrite, polybasite,acanthite, and rare native gold and electrum. The presence of base metals and/orarsenopyrite in veins and vein stockworks is only weakly correlated to gold mineralization,and therefore are not considered an indicator thereof. Where visible, gold in the form ofelectrum typically occurs as coarse aggregates or late stage fracture fillings, as rims onsubhedral quartz crystals, or as lace-like networks formed interstitially to quartz andquartz-carbonate, as well as around coarse grains of adularia, where the latter is present.Seams of electrum up to a centimetre in thickness have also been observed in sericitizedcountry rocks, with little obvious association to veins. Appreciable silver grades aregenerally present in mineralized zones where gold to silver ratios are less than 1:10; allof the known bonanza grade intersections on the Property have gold to silver ratios ofroughly 2:1. Silver-dominant veins tend to be restricted in extent. High-grade silvermineralization occurs as silver sulphides and sulphosalts that are related to adularia-richveins in which adularia pseudomorphs bladed calcite, indicative of epithermal conditions.Preliminary mineral zonation patterns (e.g. Au:Ag ratios, absence/presence of adulariaand/or base metal veining, and meso- versus epithermal vein textures) on the Propertysuggest down temperature thermal gradients towards the east (i.e. up stratigraphy) andnorth. However, it is likely that a complex combination of temporal (overprinting by laterstage lower temperature hydrothermal fluids) and spatial (distal, lower-temperature partsof the system) controls on mineralization probably occurred in response to thetelescoping porphyry system, which did not necessarily affect all previously mineralizedparts of the system equally.Mineralized quartz veins, vein networks, and vein stockworks in and around the variousmineral deposits on the Property have been affected by significant post-mineralizationdeformation. The various deformation features noted from the broader SulphuretsMining Camp (Section 7.2.3) are developed throughout the mineralized zones on theProperty. The nature, spatial, and geological associations of the mineralization within azoned alteration environment proximal to known porphyry bodies with associatedporphyry-style mineralization, coupled with the intense deformation of the bulkmineralized host-rocks, veins, and vein stockworks argue for the high-grademineralization on the Property being formed in a porphyry-driven hydrothermal system,which was deformed during subsequent post-mineral tectonism. Vein development inresponse to the later tectonic event appears to be limited to late unmineralized shallowsoutheast-dipping veins and sigmoidal shear veins (Section 7.2.3).The currently hypothesis for the mineralization on the Property is that it represents adeformed transitional meso- to epithermal porphyry-associated quartz stockwork inpervasively altered (quartz-sericite-pyrite; i.e. within the sericite alteration zone of Sillitoe2010) lower Hazelton Group rocks. The bulk mineralization may have been formedshortly after consolidation of the volcanic pile due to reactions between these rocks andseawater (Margolis 1993), possibly as a result of hydrothermal fluid circulation driven bya distal and developing porphyry system. Progressive development and telescoping ofthe porphyry system in rocks of the volcanic pile would then have resulted in widespreadand zoned porphyry-style alteration and mineralization, with the high-grade gold and goldsilvermineralization generated in a transitional meso- to epithermal environment slightlyPretium Resources Inc. 7-18 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC