Feasibility Study and Technical Report - Pretivm

Table 14.3Parameters to Describe Gold Grade Continuity for the Low-grade PopulationEstimates Within the High-grade DomainsStructure 1 Structure 2 Structure 3Area Grade Orientation NuggetSill Range Sill Range Sill RangeVOK Gold 00090 - - 10 - 60 - -WestZone-90000 0.17 0.52 10 0.31 100 - -00000 - - 10 - 50 - -Silver 00090 - - 13 - 30 - 250-90000 0.14 0.41 18 0.19 60 0.26 25000000 - - 13 - 40 - 140Gold 00120 - - 20 - 194 - --80030 0.21 0.63 25 0.16 341 - -10030 - - 7 - 35 - -Silver 00120 - - 17 - 248 - --80030 0.15 0.46 21 0.39 294 - -10030 - - 6 - 59 - -14.8.2 HIGH GRADE DOMAINS - HIGH-GRADE POPULATIONIndicator variograms for gold were calculated and modelled for the high-gradepopulations within the high-grade domains for VOK and West zones.Given the small proportion of data above the high-grade population threshold grade,experimental variograms were poorly structured for VOK and West Zone. As a result,experimental variograms were modelled for the 50th percentile of the distribution andthen adapted for the 10, 20, 30, 40, 60, 70, 80, 90, and 95th percentiles of thedistribution (Table 14.4).As with the low-grade population, due to the locally changing orientations in the VOKarea, the orientations of the variogram models were locally adjusted to reflect theinterpretation.It was not possible to model variograms for silver in West Zone. Given the highcorrelation between gold and silver (approximately 0.9 correlation coefficient), the goldvariograms were also used for the estimation of the silver high-grade population for WestZone.The upper tail of the high-grade population distributions, above the 95 percentile, wasmodelled using a hyperbolic or power mathematical model for each area for gold andsilver.Pretium Resources Inc. 14-10 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC