The Company engaged Roscoe Postle Associates Inc. (“RPA”), an independent firm of engineers and geologists, to review the Mineral Resource and Mineral Reserve model and overall LOM plan at Aurora last October. The decision was taken after it became apparent that gold production during the fourth quarter of 2018 would fall short of the forecast, developed in 2012 under prior management.

The updated Mineral Resource is based on a revised geologic interpretation of the style and structural controls for certain areas of Aurora mineralization resulting from open pit production and geologic mapping, 12,801 metres of new oriented core drilling along with relogging of some 50,000 metres of drill core. Modelling parameters, including the grade capping, domain boundaries and kriging algorithms were all modified. Reporting cut-off grades and open pit optimization assumptions were also updated. The updated Mineral Reserves and Mineral Resources statements are found below.

Mineral Resources

The Mineral Resource estimated at December 31, 2018 is summarized as follows:

Mineral Resources
As at December 31, 2018
Category Tonnage (Mt) Grade (g/t Au) Contained Metal (000 oz Au)
Open Pit
Measured 5.2 2.47 414
Indicated 3.5 2.78 310
Measured + Indicated  8.7  2.59  724 
Inferred  2.0   2.44155 
Underground
Measured 0.1 3.52 16
Indicated 31.7 3.20 3,268
Measured + Indicated 31.9 3.21 3,284
Inferred 25.6 2.27 1,861 
Total Mineral Resource
Measured 5.4 2.49 429
Indicated 35.2 3.16 3,578
Total Measured + Indicated 40.6 3.07 4,008
Total Inferred 27.5 2.28 2,016

(1) CIM (2014) definitions were followed for Mineral Resources.

(2) Open pit Mineral Resources are reported at a cut-off grade of 0.52 g/t Au for saprolite and 0.70 g/t Au for fresh rock, and underground Mineral Resources are reported at a cut-off grade of 1.2 g/t Au for Rory’s Knoll area, and 1.7 g/t Au for other areas. Cut-off grades are based on a price of $1,500 per ounce of gold and gold recoveries dependent on mine method, material type, and/or location.

(3) Minimum mining widths of 5 m for open pit and 3 m for underground were used.

(4) Bulk density is 2.8 t/m3 for fresh mineralization and 1.73 t/m3 for saprolite mineralization.

(5) Stockpile data based on EOY 2018.

(6) Mineral Resources are inclusive of Mineral Reserves.

(7) Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

(8) Numbers may not add due to rounding.

(9) The Mineral Resource estimate was prepared by David Ross, P.Geo., and Katharine Masun, P.Geo., both of RPA, a “qualified persons” under National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) and who are both independent of the Company.

Mineral Reserves

Mineral Reserves were estimated for open pit and underground production based on the 2019 revised resource model. Open pit Mineral Reserves were developed from a Lerchs-Grossmann optimization study conducted using a $1,200/oz gold price, incorporating updated operating cost assumptions, pit slope angles, dilution and mining loss factors, gold recovery and mining constraints. Final designs were developed to optimize mine design parameters and ore production schedules.

Underground Mineral Reserves were estimated for portions of the Rory’s Knoll, East Walcott, Aleck Hill and Mad Kiss deposits. Mineral Reserves included dilution and extraction factors, variable minimum mining widths depending on the deposit and cut-off grades based on operating cost assumptions and a $1,200/oz gold price.

Mineral Reserves
As at December 31, 2018
Category Quantity ('000 t) Grade (g/t Au) Contained Metal ('000 oz)
Proven
Open Pit 3,914 2.61 328
Underground 
Surface Stockpiles 784 1.24 31
Total Proven 4,698 2.38 360
Probable
Open Pit Fresh 2,217 2.63 187
Underground 20,038 2.69 1,731
Total Probable 22,255 2.69 1,918
Proven & Probable
Open Pit 6,131 2.61 515
Underground 20,038 2.69 1,731
Surface Stockpiles 784 1.24 31
Total Proven & Probable 26,953 2.63 2,278

(1) CIM (2014) definitions were followed for Mineral Reserves.

(2) Open pit Mineral Reserves are estimated at a cut-off grade of 0.60 g/t Au for saprolite and 0.83 g/t Au for fresh rock.

(3) Underground Mineral Reserves are estimated at a cut-off grade of 1.50 g/t Au for Rory’s Knoll and 2.20g/t Au for satellite deposits.

(4) Mineral Reserves are estimated using an average long-term gold price of US$1,200 per ounce.

(5) Open pit Mineral Reserves used a minimum mining width of 5 m.

(6) A minimum mining width of 5 m was used for Rory’s Knoll underground and a minimum width of 3 m was used for the satellite deposits.

(7) Bulk density is 2.8 t/m3 for fresh mineralization and 1.73 t/m3 for saprolite mineralization.

(8) Numbers may not add due to rounding.

(9) The Mineral Reserve estimate was prepared by Jason Cox, P.Eng. of RPA , a “qualified person” under NI 43-101 and who is independent of the Company.

The Company confirms that there are no known legal, political, environmental, or other risk factors that could materially affect the development of the Mineral Resources.

Scientific and technical information on this website has been reviewed and approved by Mr. Ron Stewart (P.Eng) a 'qualified person' as defined by NI 43-101. For further details, please refer to the Technical Report available on SEDAR at www.sedar.com.