Pulacayo Project Feasibility Study - Apogee Silver

Pulacayo 1 000 t/d Phase I Feasibility Study - NI 43-101 Technical Report
090644-3-0000-20-IFI-100
Figure 12.10: Certified Standard Pb128 Results - Pb % (N=91)
The PB138 certified reference material was introduced during the Phase 4 drill program to
replace PB128 and a total of 5 samples of the material were analyzed in association with drill
holes PUD207, PUD210, PUD211A, and PUD214. Ag values returned fell within -9 g/t of the
certified mean value range and average 194.20 g/t, all of which fall within mean ±2 standard
deviations control limits (Figure 12.11). The average Pb value of 1.91% falls within mean ±2
standard deviations control limits, with all but one value falling within -0.25% of the certified
mean range. One value occurs below the lower control limit (Figure 12.12). Zn results fall
within +0.11% and -0.20% of the certified mean value with 2 falling below mean ±2 standard
deviations control limits. The mean value of 2.00% falls within control limits (Figure 12.13).
Based on results presented above, it is apparent that a low bias exists in Ag and Pb results
for CDN-SE-1. This is most pronounced in the Pb data set where 15% of samples returned
values below mean ±2 standard deviations control limits. In contrast, Zn results for CDN-SE-
1 closely track the certified mean value. A low bias may also be present for Ag, Pb and Zn in
the PB138 data set but the limited number of samples (5) prevents further comment. PB128
results for all three metals typically fall within mean ±2 standard deviation project control
limits.
After review of all results, and notwithstanding the possible low bias trends noted above,
Mercator considers combined data of all certified reference material programs by Apogee to
be sufficiently consistent to support use of associated datasets for current resource
estimation purposes. However, it is recommended that potential low bias trends be
investigated further.
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