Rubicon Minerals Announces Positive Bulk Sample Reconciliation Results, Validating the 2018 Mineral Resource Estimate

TSX: RMX| OTCQX: RBYCF

TORONTO, Nov. 29, 2018 /PRNewswire/ - Rubicon Minerals Corporation (TSX: RMX| OTCQX: RBYCF) ("Rubicon" or the "Company") announces positive reconciliation results from its bulk sample program compared to the current block model estimates of the planned stope designs ("2018 Mineral Resource Block Model") at the Phoenix Gold Project (the "Project"). Rubicon believes the results validate the 2018 Mineral Resource Estimate (please refer to the Technical Report filed on SEDAR on June 13, 2018). The Company has also outlined its strategy for 2019.

Table 1: Bulk Sample Reconciliation Results

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Key Highlights from the Bulk Sample Program:

• The bulk sample results, before unplanned mining dilution, reported 32,551 t at a grade of 4.93 g/t Au containing 5,165 gold ounces, resulting in a positive reconciliation of +7.2%, +6.1%, and +13.8% compared the 2018 Mineral Resource Block Model tonnes, grade, and ounces, respectively;
• The Phoenix Gold Project mill achieved 95.1% gold recovery, with 43.2% of gold recovered from gravity, and a throughput rate of 70 tonnes per hour ("tph"), or equivalent to 1,540 tonnes per day ("tpd") on a 22-hour availability;
• Rubicon utilized the sublevel longhole stoping (bulk mining method) and achieved an average unplanned mining dilution of 8.7%; and
• A conference call with Rubicon's senior management will be held today to discuss the bulk sample reconciliation results at 10:00 am ET. Canada/ U.S. toll-free dial-in number +1 (888) 231-8191, International dial-in number +1 (647) 427-7450, webcast link: https://event.on24.com/wcc/r/1889299/C10EA8A3496852A96FA315A673E6DBFC.

Achievements Since the December 2016 Restructuring Transaction

• Rubicon Board and management team strengthened;
• Assembled an experienced and skilled site management team;
• Geologically mapped, including structural mapping, all underground excavations;
• Completed more than 45,000 metres ("m") of oriented structural, infill, step-out, and short-hole bazooka drilling;
• Engaged Golder Associates Limited ("Golder") (primary consultant) and T. Maunula & Associates (peer reviewer);
• Developed a new geological model and structural interpretation (news release March 12, 2018);
• Delivered the 2018 Mineral Resource Estimate (news release, April 30, 2018; Technical Report filed on SEDAR June 13, 2018), which demonstrated a significant increase in mineral resources for the F2 Gold Deposit;
• Successfully commissioned, operated, and de-commissioned the Project mill, achieving a throughput rate of 70 tph, or equivalent to 1,540 tpd;
• Completed a test trial mining and bulk sample processing program of 35,629 t (diluted) of mineralized material; and
• Achieved positive bulk sample reconciliation results, validating the 2018 Mineral Resource Estimate and geological model.

Strategy for 2019:

• Deliver an updated Mineral Resource Estimate, which will benefit from more than 20,000 m of oriented drilling conducted in 2017 and 2018 (first half of 2019);
• Provide a Preliminary Economic Assessment ("PEA"), at a minimum, for the Phoenix Gold Project (mid-2019);
• Continue infill and step-out diamond drilling to upgrade the mineral resource categories and grow the overall mineral resources (throughout 2019);
• Commence basic exploratory work on high-priority Close Proximity and Regional Targets in Red Lake (throughout 2019); and
• Continue to evaluate accretive business opportunities to deliver shareholder value (throughout 2019).

Comments from the President

Rubicon President and Chief Executive Officer George Ogilvie, P.Eng., stated, "We restarted activities at the Phoenix Gold Project with a goal to successfully complete a test trial mining and bulk sample processing program, and bring confidence to the 2018 Mineral Resource Estimate with positive reconciliation results. I am pleased to report that we achieved these key milestones. We believe the positive bulk sample reconciliation results validate the 2018 Mineral Resource Estimate and new geological model of the F2 Gold Deposit."

"We observed encouraging data points during the test trial mining and bulk sampling program that will have a positive impact on the potential economics of the Phoenix Gold Project; test trial mining demonstrated the amenability of bulk mining and we achieved an unplanned mining dilution of 8.7%; metallurgical recovery improved to 95.1% from the 91.5% reported in 2015; and 43.2% of gold recovery was from gravity concentration, which will reduce mill operating costs under a potential commercial production scenario. Mill operations exceeded our expectations. We operated the mill on a two-week on, two-week off basis and reached throughput rates of 70 tph, or equivalent to 1,540 tpd, which is higher than the 1,250 tpd average nameplate capacity. The mill was designed and constructed with a capacity to reach 1,800 tpd with minor modifications. This gives us significant flexibility to accept increased tonnes in future mining, if warranted."

"With a validated 2018 Mineral Resource Estimate and geological model, we now have a strong foundation to continue to advance, grow, and de-risk the Phoenix Gold Project. Going forward, our intent is to closely evaluate the positive reconciliation results, and along with additional exploration data, assess the economic viability of the Phoenix Gold Project, particularly where we can utilize significant underground infrastructure to access modelled stopes. In addition, 2019 will see us turn our attention to our high-priority Close Proximity underground exploration targets, including the past-producing McFinley target, all within 500 m of the Phoenix Gold Project shaft. We will also initiate geophysics and geochemical work on several of our Regional Exploration targets."  

Test Trial Mining, Bulk Sample Processing and Reconciliation Results

Test Trial Mining

In October 2018, Rubicon completed its test trial mining program, extracting bulk sample material from three test stopes, #015, #977, and #161, in the upper areas of the F2 Gold Deposit. These stopes were contained within the biotite and silica altered basaltic mafic volcanic flows ("High-Ti Basalt"), the main host rock of gold mineralization. These stopes had modelled grades slightly lower than the overall 2018 Mineral Resource Estimate grades but were selected due to their proximity to substantial existing underground development. This allowed Rubicon to reduce costs, timelines, and conduct the test trial mining activities during the summer and fall months in Red Lake. See Diagrams 1 to 5 at the end of the news release related to the 2018 Mineral Resource Block Model, location of the test stopes, and the grade distribution of the mineral resource blocks.  

Throughout the test trial mining process, Rubicon collected geological data from more than 10,000 underground chip and muck samples for assaying, capped at 70.0 g/t Au. These assay results supported the stope block model grades. In addition, the Company was able to confirm the geological model through the various stratigraphic zones encountered during the mapping exercise and was able to finalize stope design within the High-Ti Basalt. Short-hole bazooka air drilling on 5-metre centres provided additional data for the final stope design and further confirmed the grades of the test stopes.

Rubicon utilized sublevel longhole to test the amenability of bulk mining methods on the F2 Gold Deposit, based on its new structural and geological interpretation. The test stope dimensions ranged between 17-to-24 m in height, 16-to-38 m in strike length, and 4-to-7 m in width, and all stood near vertical. Each stope was blasted, mucked, and stockpiled separately on surface. A total of 35,629 t (diluted) of bulk sample material was mined from the three test stopes, along with 7,620 t of low-grade material, and waste material for the wet commissioning and bedding-in of the mill.

After each stope was blasted and fully mucked out, the Company conducted cavity monitoring surveys ("CMS") to assess the unplanned mining dilution from the test trial mining. Rubicon achieved unplanned dilution of 8.7%, better than the Company's estimate of 10.0%. Rubicon was able to manage the unplanned dilution due to improved drilling and blasting techniques and mining within the High-Ti Basalt.

Bulk Sample Processing and Mill Results

The Company began commissioning the Project mill in May 2018, which started with a zero-gold balance as it had been fully cleaned out in the past. The primary components of the mill circuit are the SAG and ball mills, two gravity concentrators, the electrowinning circuit and carbon in leach tanks. Rubicon processed each test stope sequentially through the mill. Contracted mill crews mainly worked on two-week on, two-week off shifts. Bulk sample material was pre-crushed to 6-inch minus prior to being fed into the mill circuit. The mill achieved a throughput rate of 70 tph, or 1,540 tpd equivalent based on a 22-hour availability. Overall mill recovery achieved was 95.1%, including approximately 43.2% recovered via gravity circuit. After processing all the bulk sample material through the mill circuit, the Company cleaned out the mill to recover material found behind the ball mill liners, pump boxes, sumps, and carbon fines. In addition, material in the tails were continually assayed to calculate overall gold recovery of the bulk sample program.

Reconciliation

Golder was hired to conduct a review of the Company's bulk sample mill results and its reconciliation to the 2018 Mineral Resource Block Model. The undiluted bulk sample mill results were 32,551 t grading 4.93 g/t Au containing 5,165 oz, achieved positive reconciliation of +7.2%, +6.1%, +13.8% compared to the 2018 Mineral Resource Block Model tonnes, grade, and ounces, respectively (see Table 1). An accounting of gold ounces in the mill was reconciled to less than 0.5%. Rubicon believes that the positive reconciliation validates the 2018 Mineral Resource Estimate, the new geological model and structural interpretation for the F2 Gold Deposit. The 2018 Mineral Resource Estimate remains current. Table 2 provides the undiluted reconciliation data for each test stope and low-grade material. Table 3 summarizes additional relevant metrics from the test trial mining and bulk sample processing program.

Table 2: Bulk Sample Results and Reconciliation Statistics (before unplanned mining dilution and mill recovery)

Table 3: Summary of Test Mining and Milling Statistics

As discussed, the overall block model grades of the test stopes mined were below the 2018 Mineral Resource Estimate grades. However, as per the 2018 Mineral Resource Estimate, there are higher-grade stopes in the upper areas and at depth at the F2 Gold Deposit for future mining under a potential commercial production scenario, after capital development has been put in place. See Diagrams 3 and 5 at the end of the news release to review the grade distribution of the 2018 Mineral Resource Estimate.

Knowledge Gained from the Test Trial Mining and Bulk Sample Processing Program

The Company gained critical information from the test trial mining and bulk sample processing program that will be important in advancing the Project. The key areas include:

• F2 Gold Deposit amenable to bulk mining: The Company demonstrated the successful implementation of the sublevel longhole stoping. Rubicon managed the unplanned mining dilution by mining within the High-Ti Basalts and using improved drilling and blasting techniques. The Company believes that future mining would entail a mix of both bulk and selective mining methods;
  
  
• Closely-spaced stope definition drilling: The Company utilized short-hole bazooka drilling on 5 m-centres to confirm the stope grades compared to the block model, prior to blasting. This short-hole drilling has also shown to provide additional information for stope design. Rubicon believes that closely-spaced definition drilling, combined with lateral and stope development that is well ahead of mining and quick assay turnaround, will be necessary to successfully mine the F2 Gold Deposit in the future;
  
  
• Higher recoveries from gravity concentrator: Rubicon achieved 43.2% of total gold recovery from gravity separation. This was higher than historical bulk sampling efforts conducted on the Project because the Company was able to optimize the existing mill process. If the Company could achieve these elevated levels of recovery from gravity in future mining, mill operating and processing costs would be lower as less reagents would be used; and
  
  
• Mill throughput operated above nameplate capacity: The mill achieved a throughput rate of 70 tph, equivalent to 1,540 tpd. The Company believes that, with minor modifications, the current design and configuration of the mill could handle up to 1,800 tpd, which would be beneficial for future bulk mining, if warranted.

2019 Path Forward

Following a successful bulk sample reconciliation, the Company believes it has a reliable geological model and a validated 2018 Mineral Resource Estimate, giving Rubicon a strong foundation to continue advancing the Phoenix Gold Project. Looking ahead, the Company endeavours to grow its mineral resources, focusing on upgrading resources to Measured and Indicated categories and expanding Inferred ounces. Rubicon anticipates delivering an updated Mineral Resource Estimate in the first half of 2019, which will benefit from data collected from infill and step-out drilling completed in late 2017 and throughout 2018. Upon the release of an updated Mineral Resource Estimate, Rubicon plans to deliver a PEA for the Project in mid-2019, or if the conditions warrant, advance work directly towards a more comprehensive technical and economic study of the project. Rubicon plans to conduct exploration work on high-priority Close Proximity Targets, including McFinley, and the Regional Red Lake Properties in 2019. Further details of the 2019 Exploration Program and budget will be provided in early 2019.

Conference Call Details

The Company's senior management team will host a conference call today, Thursday, November 29, 2018 at 10:00 am ET (7:00 am PT) to discuss the news release. Participants in Canada and the United States may join the conference call by dialing toll free +1 (888) 231-8191 or +1 (647) 427-7450 for calls outside Canada and the United States or via webcast:

https://event.on24.com/wcc/r/1889299/C10EA8A3496852A96FA315A673E6DBFC.

A recorded playback of the conference call can be accessed on the Company's website 24 hours after the end of the call at www.rubiconminerals.com.

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 for Rubicon. Curtis Clarke, Senior Mining Consultant, MMSA, and Robert Raponi, P.Eng., Metallurgical Engineer, for Golder, were responsible for the verification of gold ounces processed by the mill and the reconciliation of gold ounces allocated back to the sources. Golder also reviewed the reconciliation of tonnes, grade and ounces for each stope as compared to the Mineral Resource Model. Messrs. Clarke and Raponi are independent of Rubicon. All persons are Qualified Persons as defined by NI 43-101.

Muck assays reported are cut to 70.0 g/t Au unless otherwise stated. All samples reported herein were analysed by SGS Mineral Services of Red Lake, Ontario, an independent lab with ISO/IEC 17025-2005 accreditation for the analytical methods utilized. All muck assays reported were obtained by fire assay with AA-finish or using gravimetric finish for values over 10.0 g/t Au.  

All mill sample assays reported are uncut unless otherwise stated.  All process control grade samples were analysed at SGS Minerals, where certified analyses were conducted at their facility Lakefield, Ontario.  SGS Lakefield is independent of Rubicon Minerals and has ISO/IEC 17025-2005 accreditation for all methods utilized for the analysis of solid, solution, carbon, gravimetric concentrate and bullion samples.  All solution samples were analysed by fire assay with AA-finish.  Grinding circuit solids were conducted by AAS or gravimetric finish as applicable. All CIL carbons, gravimetric concentrates, and bullion assays were completed by fire assay with a gravimetric finish.  

For more information about the 2018 Mineral Resource Estimate and other technical and scientific aspects of the Phoenix Gold Project, including, without limitation, key assumptions, parameters and risks associated with the Phoenix Gold Project refer to the technical report entitled "National Instrument 43-101 Technical Report for the Rubicon Phoenix Gold Project" dated June 13, 2018 (the "Technical Report").

About Rubicon Minerals Corporation
Rubicon Minerals Corporation 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 over 285 square kilometres of prime exploration ground in Red Lake 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 CORPORATION
George Ogilvie, P.Eng.
President, CEO, and Director

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 with respect to mineral resource estimates; our strategy; the anticipated timing of a mineral resource estimate update, a PEA; the potential positive impacts of the bulk sampling results on the economic potential on the Phoenix Gold Project; the potential of metal recoveries to reduce operating costs; expected mill capacity; the statements made under Knowledge Gained from the Test Trial Mining and Bulk Sample Processing Program, including without limitation, statements with respect to our beliefs or expectations relating to the potential mining methods for the project, stope definition drilling, levels of recoveries from gravity and mill capacity; and the statements under 2019 Path Forward .

Forward-looking statements are based on the opinions and estimates of management and qualified persons as of the date such statements are made and represent management's and qualified persons' best judgment based on facts and assumptions (including, without limitation, assumptions discussed herein and in the Technical Report) 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; uncertainties with respect to the ability of the Company to deliver a mineral resource up-date, a PEA on the timelines contemplated; conclusions of future economic or geological evaluation (including uncertainties inherent to economic studies such as a PEA); 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, 2018 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

SOURCE Rubicon Minerals Corporation

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