Rubicon Minerals Reports 110% Increase in Measured and Indicated Resources, Further Improving Confidence at the Phoenix Gold Project

TSX: RMX | OTCQX: RBYCF

TORONTO, March 27, 2019 /CNW/ - Rubicon Minerals Corporation (TSX: RMX | OTCQX: RBYCF) ("Rubicon" or the "Company") is pleased to report an updated Mineral Resource Estimate ("2019 Mineral Resource Estimate") for the Phoenix Gold Project (the "Project"). The Company plans to file an updated NI 43-101 Technical Report for the Project within 45 days.

Table 1: 2019 Mineral Resource Estimate at 3.0 grams per tonnes of gold ("g/t Au") Cut-Off Grade¹ - Effective March 18, 2019

Table 2: Comparison between 2019³ and 2018⁴ Estimated Quantities at Reported Cut-Off Grades – 3.0  g/t Au, 3.5 g/t Au and 4.0 g/t Au

Key Points:

2019 Mineral Resource Estimate metrics, based on a 3.0 g/t Au cut-off grade:

• Measured and Indicated Resources increased 110% to 589,000 ounces of gold compared to the 2018 Indicated Resources of 281,000 ounces of gold; Measured and Indicated grades decreased 2% to 6.26 g/t Au compared to 2018 Measured and Indicated gold grades of 6.37 g/t Au;
• As a result of the successful conversion to Measured and Indicated Resources, Inferred Resources decreased 28% to 540,000 ounces of gold compared to the 2018 Inferred Resources of 749,000 ounces of gold. Inferred grades increased 9% to 6.53 g/t Au compared to the 2018 Inferred grades of 6.00 g/t Au;
• The increase in Measured and Indicated Resources is mainly attributed to the Company's successful 20,000-metre oriented infill drilling program in 2018, with the primary objective to improve confidence in the Mineral Resources above the 854-metre Level;
• The Company has increased the Measured and Indicated Resources by 456% over a two-year period from 2016⁵; and
• Rubicon commenced a Preliminary Economic Assessment (the "New PEA") on the Project, scheduled to be released in the second half of 2019. The Company will continue oriented infill drilling to expand the Measured and Indicated Resources to a threshold of more than 650,000 ounces of gold, which Rubicon believes is the required level to advance the Project to the Feasibility Study-level stage.

General observations and commentary on the 2019 Mineral Resource Estimate

• The Company has observed a relatively robust conversion rate of Inferred Resources to the Measured and Indicated categories;
• Sparsely-drilled Explore Target areas (greater than 80-metre centres) have the potential of between 0.9 million to 1.2 million tonnes of mineralized material grading between 5.0 to 7.0 g/t Au, mostly at depth;
• Test trial mining and bulk sampling program completed at the end of 2018 validates the current geological model and supports the parameters and methods used to compile the 2019 Mineral Resource Estimate; and
• Potential to further upgrade the classifications and expand the 2019 Mineral Resources with data from up to 20,000 metres ("m") of oriented drilling planned in 2019.

Potential information for consideration in the New PEA (scheduled for H2/19)

• Phoenix Gold Project mill processing metrics (gained from 2018 bulk sample program): 1,540 tonnes per day ("tpd") throughput rate (based on 22-hour mill availability) and 1,800 tpd capacity at current configuration, gold recoveries of 95.1% (43.2% from gravity);
• Bulk mining and development rates (gained from 2018 test trial mining program): Sublevel longhole mining achieved 8.7% external dilution of test stopes, current development costs, rock mechanics, ground control;
• Surface infrastructure ready for operations: Hoist fully operational, civil and earthworks in place, electric substation operational, and upgrades to the 200-person camp, tailings management facility ("TMF") and water treatment plant; and
• Significant underground infrastructure: More than 14,000 m of development already in place, including an operational shaft down to 730 m below surface, and an assessment of an underground ramp to surface.
• Uniquely positioned: The existing infrastructure provides the opportunity to move the Project back into potential commercial production in a short time frame and at lower construction risk than development-stage peers, subject to an economic conceptual mine plan.

Rubicon President and Chief Executive Officer George Ogilvie, P.Eng., stated, "The significant growth in Measured and Indicated Resources, without a significant decline in grade, brings additional confidence and validation for the Phoenix Gold Project and its potential as a commercially viable operation. We are also pleased with the improvement in ounces and grades at the 3.5 g/t Au and 4.0 g/t Au cut-off grades. We will further evaluate the continuity of mineralization at these higher cut-offs, as either of these scenarios could further improve the economics of the Project. We remain firmly on the path to building a conceptual mine plan with new economics for the Phoenix Gold Project, which will be reflected in a New PEA scheduled for the second half of 2019. We believe the New PEA has the potential to show strong economics considering all the new, fully commissioned surface and underground infrastructure already in place. The New PEA will also benefit from real, operational data collected during our recent test trial mining and bulk sampling program, where we implemented actual mining techniques that could be utilized under a potential commercial production scenario while using our own processing facility."

"Over the last two years, our management, our site operating and geology teams have delivered on all the major goals towards turning around and bringing confidence back to the Project. We believe our successful 35,000-tonne test trial mining and bulk sampling program in late 2018 validates the geological model and the mineral resources. In the coming months, we plan to enhance value to shareholders by delivering a New PEA and continue oriented infill and expansion drilling to potentially convert Inferred ounces to Measured and Indicated categories and grow the overall mineral resources at depth, where there is high-grade mineralization from historical drilling and where the deposit remains open."

"We believe Rubicon is uniquely positioned and has significant upside potential on a go forward basis. With more than 28,000 hectares of prime exploration real estate, we are the second largest property holder in the prolific Red Lake Gold Camp and we hold a very strategic position considering we own newly installed working infrastructure in the region. Combine that with a de-risked and potentially robust Phoenix Gold Project, and a management team with a strong operational and turnaround experience, we believe we have the recipe to increase shareholder value in the near- to long-term."

"I look forward to updating our shareholders when the New PEA is completed as it will provide us with a first glimpse at a conceptual long-term life of mine plan for the Phoenix Gold Project."

2019 Mineral Resource Estimate

The 2019 Mineral Resource Estimate⁶ (see Table 1 above) benefits from 551,811 m⁷ of core drilling in 1,631 drill holes. The 2019 Mineral Resource model covers a strike length of approximately 1,200 m and depths down to 1,403 m Level and remains open along strike and at depth. The 2019 Mineral Resource Estimate excludes the crown pillar and depleted resources from test trial mining.

The 2019 Mineral Resource Estimate was evaluated using a geostatistical block modelling approach constrained by mineral and lithologic 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 determined that the ID3 estimates controlled grade smoothing and achieved an appropriate grade-tonnage profile relative to the characteristics of the deposit. A nearest neighbour (NN) model was interpolated to support model validation. Density data was assigned based on average values for each lithologic 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 the Mineral Resources in the Measured, Indicated, and Inferred categories were approximately 20 m, 40 m, and 80 m centres, respectively, where geology and grade continuity were reasonably understood. Measured Resources are additionally supported with proximity to sub-level development, mapping, chip samples and supported by the bulk sample reconciliation data, where available. Measured and Indicated Resources are predominantly located near existing underground infrastructure and development.

The Mineral Resources are sensitive to the selection of reporting assumptions. The sensitivity of the Mineral Resource estimates to the selection of cut-off grade is summarized as grade tonnage data in Table 3 below. The classified Mineral Resources reported by underground level are tabulated in Table 6 (at the end of this news release). Please refer to Table 5 at the end of the news release for further details on the geological modelling and high-grade treatment strategies, including top-cut values and coefficients of variation ("CV") for each sample population. Please see Diagrams 1, 2, and 3 (at the end of this news release) showing the conceptual plan and longitudinal views of Zones 1 and 2 (the two main mineral domains) of the 2019 Mineral Resource blocks in the Measured, Indicated, and Inferred categories, and Exploration Target areas.

In late 2018, the Company completed more than 35,000 t of test trial mining and bulk sample processing, resulting in a positive reconciliation of mill results to the 2018 Mineral Resource block model estimates for the test stopes mined (for further details, see news release dated November 28, 2018). The results validate the geological model, while the test trial mining the demonstrated the amenability of sublevel longhole stoping (a bulk mining method) in the mining of the deposit.

Table 3: 2019 Mineral Resource Sensitivity Analysis at Potential Mining Cut-off Grades⁸

Comparison Between the 2019 and 2018 Minerals Resource Estimates⁹

The Company believes the 2019 Mineral Resource Estimate brings more confidence, due to the growth of Measured and Indicated Resources compared to the 2018 Mineral Resource Estimate (see Table 2 above for the comparison between 2019 and 2018 at different cut-off grades). At the reporting cut-off grade of 3.0 g/t Au, the 2019 Measured and Indicated Resources' tonnes and gold ounces increased by 113% and 110%, respectively, and grades slightly decreased 2%, compared to the 2018 Measured and Indicated Resources. The 2019 Inferred Mineral Resources' tonnes and gold ounces decreased by 34% and 28%, respectively, and grades increased 9% compared to the 2018 Inferred Resources. The significant increase in the Measured and Indicated Resources is mainly attributed to the Company's successful 2018 oriented infill drilling program of more than 20,000 m and the high conversion rates of Inferred Resources. Rubicon has changed some of the estimation parameters for the 2019 Mineral Resource Estimate. The summary of the changes is outlined in Table 4 below.

Table 4: Summary of Key Parameters that Contributed to the Changes in Mineral Resources between 2019 and 2018¹⁰

New PEA Scheduled for H2/2019

The Company has elected to conduct a New PEA to determine the economic potential of the Project, utilizing information from the 2019 Mineral Resource Estimate, and the successful test trial mining and bulk sample processing Rubicon undertook in 2018. Rubicon will continue exploration drilling to expand the Measured and Indicated Resources to more than 650,000 ounces, which is the current main threshold that the Company believes is needed to advance the Project to a Feasibility Study. Work on the New PEA for the Project is underway and is scheduled to be delivered in the second half of 2019. The New PEA will provide a preliminary glimpse at a potential production schedule and associated cash flows and will benefit from the following information:

• Mill processing: Rubicon owns a state-of-the-art mill that was constructed in 2015, with a capacity of 1,800 tpd based on its current configuration. In 2015, more than 40,000 t of mineralized material were processed through its mill, achieving gold recoveries of 91.5%. In 2018, as part of the Company's successful test trial mining and bulk sampling program, Rubicon processed more than 35,000 t of mineralized material through its mill, achieving throughput and gold recoveries of 1,540 tpd (based on a 22-hour mill availability) and 95.2% (with 43.2% via gravity), respectively.
• Bulk mining: The Company has successfully demonstrated the amenability of sublevel longhole stoping during its 2018 test trial mining program, achieving external dilution of 8.7%. Average dimensions of the test stopes were 21 m height by 27 m strike length by 6 m stope width, however, Rubicon believes that it has the potential to increase stope dimensions;
• Surface infrastructure ready for operations: Rubicon has a fully operational hoist, all the civil and earthworks in place, and a working electrical substation. The Company believes some capital is required for upgrades to the 200-person camp, adding another lift to the TMF to account for bulk mining, and an ammonia reactor (to treat ammonia) upgrade to the water treatment plant. The Company has roughly C$300 million in sunk capital consisting of hard, tangible assets at site, including its new state-of-the-art mill; and 
• Significant underground infrastructure: The Project has more than 14,000 m of underground development already in place, included an operational shaft down to 730 m below surface and the capacity to be able to hoist more than 3,000 t of material a day. The Company will assess the economics of completing an underground ramp to surface to exclusively transport personnel and equipment to the underground.

Next Steps

The Company believes it can potentially improve upon the 2019 Mineral Resource Estimate in the following areas:

• Targeted infill and step-out drilling in areas containing Inferred Resources and Exploration Targets¹¹: Rubicon intends to upgrade resources to the higher Measured and Indicated categories by drilling areas at depth of the deposit where existing drill spacing is on 40-m centres or more. Furthermore, Rubicon has identified Exploration Target areas¹¹ (greater than 80-metre centres) potentially between 0.9 million to 1.2 million tonnes of sparsely drilled mineralized material with grades potentially between 5.0 to 7.0 g/t Au where the Company intends to infill drill. Rubicon has budgeted up to 20,000 m of drilling from the 610 m and 685 m Levels.
• Evaluating McFinley and Close Proximity Targets: Rubicon is evaluating Mineral Resource data from the historic McFinley Deposit, located near existing underground development at the Project, using current standards and parameters, which could be potentially included in any future Mineral Resource Estimate. The Company is also evaluating historical drill data from its Close Proximity Targets (Peninsula, CARZ, and Island Zones) located within two kilometres northeast of the Project, which could possibly be included in any future updated Mineral Resource Estimate.
• F2 Gold Deposit remains open at depth and along strike: Historical drilling intersected high- grade intercepts to a depth of 1,600 m below surface, well below the bottom of the 2018 Mineral Resource Estimate at 1,403 m Level. These intercepts warrant follow up drilling in the future.

Qualified Persons and Quality Assurance and Quality Control (QA/QC)

The content of this news release has been read and approved by George Ogilvie, P.Eng., President and CEO, and Michael Nerup, P.Geo., Senior Site Geologist for Rubicon, and Tim Maunula, P.Geo. for T. Maunula & Associates Consulting Inc. ("TMAC"). All are Qualified Persons as defined by NI 43-101.

Underground drilling was conducted by Boart Longyear Drilling of Haileybury, Ontario and was supervised by the Rubicon exploration team. All assays reported are uncut unless otherwise stated. All samples reported herein were performed by SGS Mineral Services of Red Lake, Ontario. All NQ core assays reported were obtained by fire assay with AA-finish or using gravimetric finish for values over 10.0 g/t Au.

Intercepts cited do not necessarily represent true widths, unless otherwise noted, however drilling is generally intersecting interpreted mineralized zones at angles between -30o and +30o. True width determinations are estimated at 65-80% of the core length intervals for the 305 m Level drilling, and estimated at 75-95% of the core length for the 610 and 685 m Level drilling. Rubicon's quality control checks include insertion of blanks, standards and duplicates to ensure laboratory accuracy and precision.

About Rubicon Minerals Corporation
Rubicon Minerals Corp. is an advanced gold exploration company that owns the Phoenix Gold Project, located in the prolific Red Lake gold district in northwestern Ontario, Canada. Additionally, Rubicon controls the second largest land in Red Lake consisting of over 285 square kilometres of prime exploration ground, and more than 900 square kilometres of mineral property interests in the emerging Long Canyon gold district that straddles the Nevada-Utah border in the United States. Rubicon's shares are listed on the Toronto Stock Exchange (RMX) and the OTCQX markets (RBYCF). For more information, please visit our website at www.rubiconminerals.com.

Rubicon Minerals Corp.
George Ogilvie, P.Eng.
President, CEO, and Director

Table 5: Further Details on Geological Modelling and High-Grade Treatment Strategy

Cap Values for Zones 1, 2, 3, and 4:

CV for Zones 1, 2, 3, and 4 Uncapped:

Std Dev – Standard Deviation; CV – coefficient of variation

CV for Zones 1, 2, 3, and 4 Uncapped:

Std Dev – Standard Deviation; CV – coefficient of variation

Table 6: Classified 2019 Mineral Resources by Underground Level at 3.0 g/t Au Cut-off Grade¹²

Diagram 1: 2019 Mineral Resource Classification– Plan View, 305 m Level (Looking Grid North)

Diagram 2: 2019 Measured and Indicated, and Inferred Mineral Resource Classification Zone 1 (F2 Basalt) – Longitudinal View Looking Grid East

Diagram 3: 2019 Measured and Indicated, and Inferred Mineral Resource Classification Zone 3 (F2 Basalt) – Longitudinal View Looking Grid East

Cautionary Statement regarding Forward-Looking Statements and other Cautionary Notes

This news release contains statements that constitute "forward-looking statements" and "forward looking information" (collectively, "forward-looking statements") within the meaning of applicable Canadian and United States securities legislation. Generally, these forward-looking statements can be identified by the use of forward-looking terminology such as "believes", "intends", "may", "will", "should", "plans", "anticipates", "potential", "expects", "estimates", "forecasts", "budget", "likely", "goal" and similar expressions or statements that certain actions, events or results may or may not be achieved or occur in the future. In some cases, forward-looking information may be stated in the present tense, such as in respect of current matters that may be continuing, or that may have a future impact or effect. Forward-looking statements reflect our current expectations and assumptions, and are subject to a number of known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any anticipated future results, performance or achievements expressed or implied by the forward-looking statements.

Forward-looking statements include, but are not limited to statements regarding the anticipated timing of the filing of the NI 43- 101 Technical Report, the reasons for the increase in Measured and Indicated Resources, the anticipated timing of the release of the PEA, the anticipated future infill drilling to be completed, along with the threshold level of Measured and Indicated Resources to advance the Project to the Feasibility Study-level stage, the potential amount of mineralized material and its grade to be realized from the Explore Target areas, the impact of the data from the 20,000 m of drilling planned in 2019 on the 2019 Mineral Resource Estimate, the potential information for consideration in the PEA, the potential advancement of the Phoenix Gold Project to a viable commercial operation, the potential results of the New PEA, the anticipated outcome of further oriented infill and expansion drilling of the deposit, the defendability of the parameters used in the 2019 Mineral Resource Estimate, the nature of the 2019 Mineral Resource Estimate when compared with the 2018 Mineral Resource Estimate, the potential to expand the Project's mill capacity, the potential to increase stope dimensions of the Project, the estimated value of the tangible assets at the Project site, the potential to improve the quantities and classification of the 2019 Mineral Resource Estimate, the further steps necessary to potentially improve upon the 2019 Mineral Resource Estimates, including targeted infill and step-out drilling to potentially convert Inferred Resources to Indicated Resources, using the results from the bulk sampling program for reconciliation and validation purposes, the evaluation of the McFinley Deposit and other close proximity targets for potential inclusion in a future Mineral Resources Estimate, and follow-up drilling of the F2 Gold Deposit at depth and along strike.

Forward-looking statements are based on the opinions and estimates of management as of the date such statements are made and represent management's best judgment based on facts and assumptions that management considers reasonable. If such opinions and estimates prove to be incorrect, actual and future results may be materially different than expressed in the forward-looking statements.

Forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Rubicon to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Such factors include, among others: possible variations in mineralization, grade or recovery or throughput rates; uncertainty of mineral resources, inability to realize exploration potential, mineral grades and mineral recovery estimates; actual results of current exploration activities; actual results of reclamation activities; uncertainty of future operations, delays in completion of exploration plans for any reason including insufficient capital, delays in permitting, and labour issues; conclusions of future economic or geological evaluations; changes in project parameters as plans continue to be refined; failure of equipment or processes to operate as anticipated; accidents and other risks of the mining industry; delays and other risks related to operations; timing and receipt of regulatory approvals; the ability of Rubicon and other relevant parties to satisfy regulatory requirements; the ability of Rubicon to comply with its obligations under material agreements including financing agreements; the availability of financing for proposed programs and working capital requirements on reasonable terms; the ability of third-party service providers to deliver services on reasonable terms and in a timely manner; risks associated with the ability to retain key executives and key operating personnel; cost of environmental expenditures and potential environmental liabilities; dissatisfaction or disputes with local communities or First Nations or Aboriginal Communities; failure of plant, equipment or processes to operate as anticipated; market conditions and general business, economic, competitive, political and social conditions; our ability to generate sufficient cash flow from operations or obtain adequate financing to fund our capital expenditures and working capital needs and meet our other obligations; the volatility of our stock price, and the ability of our common stock to remain listed and traded on the TSX.

Forward-looking statements contained herein are made as of the date of this news release and Rubicon disclaims any obligation to update any forward-looking statements, whether as a result of new information, future events or results or otherwise, except as required by applicable securities laws. Readers are advised to carefully review and consider the risk factors identified in the Company's annual information form dated March 22, 2019 under the heading "Risk Factors" and in other continuous disclosure documents of the Company filed at www.sedar.com for a discussion of the factors that could cause Rubicon's actual results, performance and achievements to be materially different from any anticipated future results, performance or achievements expressed or implied by the forward-looking statements. Readers are further cautioned that the foregoing list of assumptions and risk factors is not exhaustive and it is recommended that prospective investors consult the more complete discussion of Rubicon's business, financial condition and prospects that is included in this news release. The forward-looking statements contained herein are expressly qualified by this cautionary statement.

Cautionary Note to U.S. Readers Regarding Estimates of Measured, Indicated and Inferred Resources

This news release uses the terms "Measured" and "Indicated" Mineral Resources and "Inferred" Mineral Resources. The Company advises U.S. investors that while these terms are recognized and required by Canadian securities administrators, they are not recognized by the SEC. The estimation of "Measured" and "Indicated" Mineral Resources involves greater uncertainty as to their existence and economic feasibility than the estimation of Proven and Probable Reserves. The estimation of "Inferred" resources involves far greater uncertainty as to their existence and economic viability than the estimation of other categories of resources. It cannot be assumed that all or any part of a "Measured", "Inferred" or "Indicated" mineral resource will ever be upgraded to a higher category.

Under Canadian rules, estimates of "inferred mineral resources" may not form the basis of feasibility studies, pre-feasibility studies or other economic studies, except in prescribed cases, such as in a preliminary economic assessment under certain circumstances. The SEC normally only permits issuers to report mineralization that does not constitute "reserves" as in-place tonnage and grade without reference to unit measures. Under U.S. standards, mineralization may not be classified as a "reserve" unless the determination has been made that the mineralization could be economically and legally produced or extracted at the time the reserve determination is made. U.S. investors are cautioned not to assume that any part or all of a "measured", "indicated" or "inferred" mineral resource exists or is economically or legally mineable. Information concerning descriptions of mineralization and resources contained herein may not be comparable to information made public by U.S. companies subject to the reporting and disclosure requirements of the SEC.

 The Toronto Stock Exchange has not reviewed and does not accept responsibility for the adequacy or accuracy of this release.

View original content to download multimedia:http://www.prnewswire.com/news-releases/rubicon-minerals-reports-110-increase-in-measured-and-indicated-resources-further-improving-confidence-at-the-phoenix-gold-project-300819339.html

SOURCE Rubicon Minerals Corp.