Feasibility Study and Technical Report - Pretivm

Figure 7.6 (con’t)Brucejack Property Geology (Figure 7.5) LegendWell-bedded green, maroon, and grey andesitic to dacitic pyroclastic and epiclastic rockscomparable to rocks of the Betty Creek Formation, are present to the northeast andsoutheast of Brucejack Lake, off the eastern edges of the Brucejack geological map inFigure 7.5.There are almost no intrusive rocks east of the Brucejack Fault, other than a limitednumber of narrow post-mineral and post-tectonic amygdaloidal mafic dykes. This is incontrast to the increased abundance in intrusives noted west of the Property (Kirkhamand Margolis 1995).7.3.2 ALTERATION AND MINERALIZATIONThe prominent gossanous alteration features on the Property define a distinctive northsouthtrending and west-concave arcuate belt that is generally located on the east of theBrucejack Fault. This belt is characterized by a broad band of variably but generallyintensely quartz-sericite-pyrite altered rocks of up to several hundred metres or moreacross, and approximately 5 km in strike extent. The quartz-sericite-pyrite alterationtypically contains between 2 and 20% pyrite, and, depending on the alteration intensity,can preclude protolith recognition.High-grade gold (± silver) mineralization is predominantly located within this alterationband and is generally associated with vein-stockwork systems of varying intensity. Thesestockwork systems display good continuity along-strike (several tens of metres to severalhundreds of metres) and are characterized by the presence of mesothermal toepithermal veins of quartz, quartz-carbonate, quartz-adularia, and pyrite that are typicallyon the order of millimetres to tens of centimetres in thickness and form intensecrosscutting networks within the stockworks. In rare cases, the veins may range up tonearly 10 m in thickness. Most high-grade zones are either on the margins of, orcontained within, a zone of bulk mineralization. Bulk low-grade mineralization zones(locally up to several grams per tonne gold) tend to be associated with disseminatedanhedral pyrite. Zones and veins of euhedral pyrite are barren.Pretium Resources Inc. 7-17 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC