For the 2017 Mineral Resource Estimate (amended from 2016), Tetra Tech ("Tt") completed an independent mineral resource and reserve estimate of the contained copper in the Zonia deposit. The following table shows the Tt estimated Zonia classified mineral resources at a base case cutoff of 0.2 % total copper ("TCu"). Mineral resources were reported within a Whittle(r) shell generated using the Lerchs-Grossman algorithm using $2.50/lb copper. Mineral resources within an optimized shell are not mineral reserves and do not have demonstrated economic viability.
Tetra Tech 2017 Zonia Classified Mineral Resources Base Case
Classification | Cutoff | Tons | Grade | Cu lbs |
---|---|---|---|---|
Measured | 0.2 | 15.4 | 0.42 | 129.3 |
Indicated | 0.2 | 61.4 | 0.31 | 380.6 |
Measured + Indicated | 0.2 | 76.8 | 0.33 | 510.0 |
Inferred | 0.2 | 27.2 | 0.28 | 154.6 |
Notes:
For the PEA, GRE used the 2016 Tetra Tech block model to generate new pit shells at metal prices from $0.50/lb to $5.00/lb Cu, in $0.25/lb increments. Preliminary analysis indicated that the $2.00/lb pit had the greatest potential for economic success. The pit shell for the $2.00/lb pit was imported into Geovia GEMS(tm) to design the ultimate pit layout using 45 degrees batter angle, 20-foot bench height, 12.7-foot bench width, 10% ramp grade, and ramp width of 100 feet for all but the lowest four benches, which were given a single-wide 50-foot ramp width.
The following table shows the estimated classified mineral resources within the $2.00/lb pit at various copper cutoffs.
GRE 2018 Pit-Constrained Mineral Resources at Various Copper Cutoffs
Classification | Tons (millions) | Cu Grade (%) | Cu Pounds (millions) |
---|---|---|---|
0.12% Cutoff | |||
Measured | 15.5 | 0.415 | 125.4 |
Indicated | 65.1 | 0.297 | 378.3 |
Measured + Indicated | 80.5 | 0.319 | 503.7 |
Inferred | 26.4 | 0.265 | 153.3 |
0.16% Cutoff | |||
Measured | 15.0 | 0.418 | 124.7 |
Indicated | 58.2 | 0.309 | 362.0 |
Measured + Indicated | 73.2 | 0.331 | 486.7 |
Inferred | 22.2 | 0.279 | 143.1 |
0.20% Cutoff | |||
Measured | 14.3 | 0.419 | 124.5 |
Indicated | 48.3 | 0.310 | 361.1 |
Measured + Indicated | 62.5 | 0.332 | 485.6 |
Inferred | 17.0 | 0.284 | 138.6 |
0.22% Cutoff | |||
Measured | 13.7 | 0.430 | 121.3 |
Indicated | 42.0 | 0.329 | 321.4 |
Measured + Indicated | 55.7 | 0.351 | 442.6 |
Inferred | 14.4 | 0.304 | 117.0 |
Notes:
Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the Mineral Resources will be converted into Mineral Reserves. Inferred resources are that part of a Mineral Resource for which quantity and grade or quality are estimated on the basis of limited geological evidence and sampling. Geological evidence is sufficient to imply but not verify geological and grade or quality continuity. It is reasonably expected that the majority of Inferred Mineral Resources could be upgraded to Indicated Mineral Resources with continued exploration.