Mineral Resources

2018 Mineral Resource Estimate of the Phoenix Gold Project at 3.0 g/t Au Cut-Off Grade (Effective April 30, 2018)



The 2018 Mineral Resource Estimate benefits from 483,303 m  of core drilling in 1,343 drill holes carried out from February 2008 to November 2017, along with the re-logging of approximately 10,000 m of historical core, detailed structural mapping, and existing data from development mapping and underground wall sampling (chip samples). The 2018 Mineral Resource model covers a strike length of approximately 1,200 m and depths up to 1,350 m and remains open along strike and at depth. The 2018 Mineral Resource Estimate excludes the crown pillar, depleted resources, and information below the 1,350 m elevation. 

2018 Mineral Resource Estimate at 3.0 grams per tonnes of gold (“g/t Au”) Cut-Off Grade  - Effective April 30, 2018

Resource Category Quantity
(000' tonnes)
(g/t Au)
Contained Ounces
Measured (M) 188 6.80 41,000
Indicated (I) 1,1866.30240,000
Total M + I1,3746.37281,000
Inferred 3,884 6.00 749,000

Effective date for this Mineral Resource is April 30, 2018
Mineral Resource Estimate uses a break-even economic cut-off grade of 3.0 g/t Au based on assumptions of a gold price of US$1,300 per ounce, an exchange rate of US$/C$ 0.77, mining cash costs  of C$97/t, processing costs of C$20/t, G&A of C$5/t, sustaining capital C$10/t, refining, transport and royalty costs of C$53/oz, and average gold recoverability of 92% 
Mineral Resource Estimate reported from within an envelope accounting for mineral continuity
Mineral Resources are not Mineral Reserves and do not demonstrate economic viability
There is no certainty that all or any part of this Mineral Resource will be converted into Mineral Reserve
All figures are rounded to reflect the relative accuracy of the estimates and totals may not add correctly

The 2018 Mineral Resource Estimate should be read in conjunction with the tables and figures included in the body and presented at the end of the news release dated April 30, 2018. There is no certainty that the Inferred Mineral Resources will be converted to the Measured and Indicated Mineral Resource categories, that the Measured and Indicated Mineral Resources will be converted to the Proven and Probable Mineral Reserve categories and there is no certainty that the updated Mineral Resource statement will be realized. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability; the estimate of Mineral Resources in the updated Mineral Resource statement may be materially affected by environmental, permitting, legal, title, taxation, socio-political, marketing, or other relevant issues.


2018 Mineral Resource Estimate – Further Details

The 2018 Mineral Resource Estimate was evaluated using a geostatistical block modelling approach constrained by mineral and stratigraphic domains interpreted from the drill hole and mapping data. The block model grades were interpolated using inverse distance cubed (“ID3”), which the Company evaluated as the most representative method. Rubicon assessed other grade interpolation methodologies, including ordinary kriging (“OK”) and inverse distance squared (“ID2”), and determined that the ID3 estimates controlled grade smoothing the best and achieved an appropriate grade-tonnage profile relative to the characteristics of the deposit. Density data was assigned based on average values for each stratigraphic unit.

The block model was classified in accordance with Canadian Institute of Mining, Metallurgy and Petroleum (“CIM”) Definition Standards for Mineral Resources and Mineral Reserves (May 2014). Drill spacing for Mineral Resources in the Measured, Indicated, and Inferred categories were approximately up to 20 m, 20-to-40 m, and 40-to-80 m centres, respectively, where geology and grade continuity were reasonably understood. Measured Resources required a minimum of a 20 m by 20 m drill spacing with sub-level development, mapping, chip samples and supported by reconciliation where available. Measured and Indicated Resources are all located near existing underground infrastructure and development. 

At a 3.0 g/t Au cut-off grade for the 2018 Mineral Resource Estimate, Rubicon is evaluating a potential bulk mining scenario for the F2 Gold Deposit. The Company is currently testing the sub-level long-hole mining method for its three test stopes and anticipates extracting a bulk sample between 25,000 to 30,000 tonnes, which will be processed at the Company’s mill. Rubicon intends to reactivate its mill later this year. Observations and results from its test mining activities will allow the Company to confirm the amenability of possible bulk mining methods.