Project Mineral Reserves

The table below presents the Mineral Reserve estimate for the Project (effective as of October 22, 2021). These Proven and Probable Mineral Reserves formed the basis of the economic evaluation of the Project and are based on a gold price of US$1,680 per ounce. The economic assumptions and parameters used for the calculation of reserves are the same as those used for the PFS financial model. Note that tonnages presented are in the metric system.

Livengood Gold Project Mineral Reserve Estimate

1. Mineral Reserves are reported using the 2014 CIM Definition Standards and are estimated in accordance with 2019 CIM Best Practices Guidelines.
2. Mineral Reserves are estimated using a gold price of US$1,680 per ounce, and consider a 3% royalty, 1.80/oz for smelting, refining, and transportation costs, and a gold payable of 99.9%
3. Metallurgical recovery curves were developed for each rock type, with the Mineral Reserves having the following tonnage weighted averages; 83.3%, for Rocktype 4, 79.8% for Rocktype 5, 73.5% for Rocktype 6, 66.4% for Rocktype 7, 58.7% for Rocktype 8 and 57.1% for Rocktype 9, including 22% for massive stibnite mineralization.
4. As a result of the complex metallurgical recovery equations, it is difficult to determine specific cut-off grades. The following presents the lowest gold grades for each rocktype that are processed in the life of mine plan; 0.26 g/t for Rocktype 4, 0.28 g/t for Rocktype 5, 0.31 g/t for Rocktype 6, 0.31 g/t for Rocktype 7 and 0.42 g/t for Rocktype 8 and 0.42 g/t for Rocktype 9.
5. The strip ratio for the open pit is 1.2 to 1.
6. The Mineral Reserves are inclusive of mining dilution and ore loss.
7. The reference point for the Mineral Reserves is the primary crusher.
8. Totals may not add due to rounding.
9. The foregoing mineral reserves are based upon and are included within the current mineral resource estimate for the Project.

Project Mineral Resources

The mineral resource estimates set forth in the PFS (“2021 MRE”) have been prepared by Resource Development Associates Inc. (“RDA”). Compared to the mineral resource estimates in the 2017 Report, the 2021 MRE included spatial modelling of the occurrence of antimony throughout the deposit as well as modelling of the locations of massive stibnite veins within the deposit. These details add valuable contributions to the reasonable prospects of eventual economic extraction of gold for the Project. Gold mineralization has been interpolated into 10 x 10 x 10-meter blocks using inverse distance cubed (ID3) estimation techniques, believed to more conservatively support future production schedules as compared to the 2017 Report, which was based on Multiple Indicator Kriging of 15 x 15 x 10-meter blocks parceled into 7.5 x 7.5 x 10-meter selective mining units.

Table 1 Mineral Resource Estimate – Open Pit Constrained – Economic Parameters at Gold Selling Price of US$1,650 per Troy Ounce. Resources Estimated at Variable Au Cutoff Grades – as described in Table 2

(Qualified Person: Scott Wilson CPG; Effective August 20, 2021)

Mineral resources for the Project were determined based upon a combination of 776 reverse circulation and diamond drillholes comprising 147,658 assays of which 125,450 assays measured detectable Au mineralization. High grade Au outliers were capped prior to compositing. Assays were composited to nominal ten-meter lengths, yielding 20,806 individual samples which were used for the estimation of mineralization. Mineralization was determined using inverse distance cubed estimation techniques, adhering to geological constraints throughout the mineral deposit.

In order to define the quantities of Au with “reasonable prospects for economic extraction” by open pit methods, RDA determined pit constraining limits using the Lerchs-Grossman^© economic algorithm which constructs lists of related blocks that should or should not be mined. The final list defines a surface pit shell that has the highest possible total value, while honoring the required surface mine slope and economic parameters. Mineral resources were determined at a gold selling price of US$1,650.

The parameters listed in Table 2 define a realistic basis to estimate the mineral resources for the Project and are based on the extensive scientific, metallurgical and engineering based analyses that have been completed by Tower Hill Mines since 2006. Mineral resources for the Project have been limited to mineralized material that occurs within the pit shells and which could be scheduled to be processed based on the defined cut-off grades. All other material within the constraining pit, which was not classified according to CIM Definition Standards, was characterized as non-mineralized material.