Feasibility Study and Technical Report - Pretivm

maximum number of samples was kept small in the second search pass to prevent singleextreme grades influencing the block estimates at a great distance.The interpolation was controlled by:• minimum/maximum numbers of composites: West Zone: 8/20 per block (2/8 for pass 2) VOK: 6/16 per block (2/6 for pass 2)• discretisation: 1 by 1 by 1 (indicator kriging)• maximum number of composites per hole: 10• search ellipse: West Zone: 50 m by 50 m by 50 m (150 m by 150 m by 150 m for pass 2) VOK: 50 m by 50 m by 20 m (150 m by 150 m by 60 m for pass 2).14.10.3 HIGH-GRADE DOMAINS - PROBABILITYThe proportion of the higher-grade mineralization was estimated into each block andused to combine the two estimates in the determination of the overall block grade. Forexample, if a block had a probability of 5% high grade then the final block grade wouldcombine 95% of the low-grade estimate with 5% of the high-grade estimate. Theinfluence of the high-grade population above the 95 percentile is therefore greatlyrestricted.An indicator estimate was run at the population threshold for gold and silver (5 g/t Auand 50 g/t Ag for VOK, and 5 g/t Au and 300 g/t Ag for West Zone), using all of the datawithin the mineralized high-grade domains.Estimation for VOK and West Zone was into the small-scale discretized blocks used forthe high-grade population estimates. The resultant probabilities were re-blocked intoparent blocks the same size of those used for the lower-grade population estimates.The same domains and boundary conditions applied to the high-grade and low-gradepopulations were used for the probability estimate. Probability for gold and silver wereinterpolated using 1.5 m composites. Estimation parameters were established from thevariography analysis and used a single search pass only to prevent spreading theprobability estimate too far in all areas except VOK.In VOK there has been a significant increase in drilling and the use of a single search forthe probability resulted in over smoothing of the estimate. As a result a two pass searchwas used with the first search kept very tight to prevent over smoothing in well informedareas. The second search was set similar to the single search used for the other areas.The maximum number of samples was also reduced in the first search pass and themaximum number of composites per drillhole was reduced.Pretium Resources Inc. 14-15 1291990200-REP-R0012-02Feasibility Study and Technical Report on the BrucejackProject, Stewart, BC