Vancouver, BC – Coast Copper Corp. (“Coast Copper” or the “Company”; TSX-V: COCO) is pleased to announce a National Instrument (“NI”) 43-101 Mineral Resource Estimate (the “2023 MRE”) for the gold-copper Merry Widow open pit located at its optioned Empire Mine property (“Empire Mine”, “Empire” or the “Property”). The 2023 MRE1 updates and improves the 2008 MRE2 published by Grande Portage Resources Ltd and should be considered Coast Copper’s first proof of concept with the results feeding into a scoping study for a “hub and spoke” processing facility previously announced by Coast Copper (see news release March 21, 2023). The updated resource and modeled pit case are shown in Figure 1.
Highlights from Coast Copper’s 2023 MRE include:
- Geological proof of concept that copper-gold-magnetite mineralization is structurally controlled at intersections of both thrust and high angle faults, in addition to dyke margins,
-Inferred Mineral Resource Estimate of 81,322 ounces (“oz”) gold equivalent (“AuEq”) grading 3.52 grams per tonne (“g/t”) gold (“Au”) and 0.50% copper (“Cu”) [4.258 g/t AuEq] contained within 0.59 million metric tonnes (“MT”) (using a net smelter return (“NSR”) cut-off of $30 CDN) (see Table 1)1,
-Increase in average grade, and resource constrained to “reasonable prospects of eventual economic extraction” pit shell,
-Conservative metal recoveries assumption of 60% Au and 77% Cu based on limited 2008 metallurgical work,
-Global in-situ strip ratio of 5.5:1.0 based on a conservative 50-degree pit slope angle,
-Geological model indicates potential targets on strike and at depth of current 2023 MRE,
-Merry Widow 2023 MRE represents only 200 meters (“m”) strike length of an overall >2 kilometers (“km”) trend.
The Merry Widow open pit area is one of 15 exploration target zones at Empire identified from historical drilling by previous operators and more recent exploration conducted by Coast Copper. Empire also includes a target zone at the historical Benson Lake Mine/Old Sport Horizon with copper and gold potential covering approximately 3 square kilometers (“km2”) based on historical exploration and mining completed by Cominco Resources3. To note, the 2023 MRE does not include the historical Benson Lake Mine reserves.
The updated resource is presented in Table 1 and illustrated in Figure 2. Sue Bird, M.Sc., P.Eng., of Moose Mountain Technical Services (“MMTS”) was contracted to calculate the 2023 MRE published within this news release. An updated technical report will be filed on Coast Copper’s website and with SEDAR within 45 calendar days of this disclosure.
Adam Travis, Coast Copper’s CEO, commented: “The Empire Mine Property covers 23 mineral occurrences, including 3 past-producing open pit and two past-producing underground mines. The 2023 MRE at the Merry Widow open pit covers an area approximately 200 m by 100 m which is a small portion of the known exploration footprint on the Property. Empire includes 15 identified exploration target zones of which the Merry Widow open pit is the first that Coast Copper has tested. Therefore, this 2023 MRE should be considered a proof of concept that takes the historical information, combines it with our recent drilling and geophysics programs, and delivers a NI 43-101 mineral resource estimate that shows substantial improvements over the previously published historical estimate in 2008 (the “2008 MRE”). Furthermore, the 2023 MRE covers just 25 m of the known 200 m strike length between the Merry Widow open pit and the Raven pit located to the north. We expect to publish an Exploration Target Range in due course as we systematically look to unlock the known potential at Empire.”
The work completed on the geological model provides proof of concept that zones of significant mineralization occur not only along the intrusive dyke margins, but also along the structural intersections of thrust and high angle faults (see Figure 2). As previously announced by Coast Copper, (see news release January 18, 2023), this reinforces the potential for multiple high-grade, near-surface targets along the 2 km upper Merry Widow trend.
Updating the previous geological model and constraining the resource to “reasonable prospects of eventual economic extraction” pit shell resulted in an increase of average gold and copper grades as compared to the 2008 resource. The gold grade increased by 73% from 2.03 g/t to 3.52 g/t and the copper grade increased by 50% from 0.34% to 0.51% (excluding any potential credits for cobalt, silver, and magnetite). Future work will include further investigation into these potentially significant accessory metal constituents.
Due to limited metallurgical data from test work conducted in 2008 from drill core samples, the 2023 MRE applied conservative recoveries of 60% Au and 77% Cu. In 2010, further metallurgical work by Grande Portage reported recoveries of 95% Au and 88% Cu from a small bulk sample. Given the discrepancy between recovery values, the Company plans to complete a proper metallurgical test program on the representative material types to improve metal recoveries in the near future.
The 2023 MRE examined possible parameters affecting economics such as pit shapes and pit slopes. A very conservative pit slope of 50-degrees was used even though the previous Merry Widow pit, which ceased production in 1968, currently stands up well with a significantly steeper overall pit slope. To maximize the pit slope angles and reduce strip ratio, Coast Copper will look at completing a geotechnical assessment of the open pit and lab testing for optimal pit design.
Due to a lack of modern QA/QC standards and incomplete sampling from 1989-1990 drill assay data, some data from the field programs was not able to be used in the 2023 MRE. Although some data was not used in the calculation of the 2023 MRE, the assay data and geological observations will be used to target historically mineralized areas, especially those that are noted to occur outside the 2023 MRE. The 500 m long Kingfisher Adit was established by Empire Mines in 1960, approximately 107 m below the bottom of the Merry Widow pit, to extract further magnetite resource by block caving methods below the Merry Widow pit. Rock chip sampling, geological observations and observed mineralization within this adit during the 2022 field program have returned values up to 3.4 g/t Au and 2.6% Cu (see news release August 15, 2022), indicating potential resource expansion at depth.
Coast Copper expects to outline additional mineral resource potential for the Merry Widow open pit area in an upcoming press release. Exploration efforts will focus on expanding the Merry Widow mineralized trend along strike to the north-northeast towards Raven Pit/Bluff as well as to the south towards Marten, where it has completed initial drill testing that has highlighted the potential for the system to occur in both directions. Further exploration efforts will be followed at depth below the Merry Widow open pit where copper and gold mineralized skarn as well as magnetite skarn were sampled along the Kingfisher Underground which is up to 40 m below the 2023 MRE. The Company expects to complete this in due course.
Mirva Properties Ltd (“Mirva”) has retained a 2% NSR royalty on the Empire Mine property, of which 1% may be purchased for $1,000,000 at any time up to 120 days after commencement of commercial production. The Empire Option Agreement has been structured such that this NSR royalty plus all other NSR royalties which may currently exist and be payable on the Empire Mine property will not exceed in aggregate 2.5% before buydowns.
Key Assumptions and Methods Used for Mineral Resource Estimate
Updates from the previous model by Giroux in 2008 included the addition of drillholes from Coast Copper’s 2021 drill program, incorporating results from 1989 underground chip sampling for interpretations, updated interpretations of the mineralized resource envelope, drillhole data validations, updated grade capping and the use of current economic factors to develop a ‘reasonable prospects of eventual economic extraction’ pit.
Implicit modeling tools were used to develop a mineralization envelope which targets a minimum $20 NSR value cutoff in a smooth and continuous shape. The shape was then clipped away from mined out areas. The clipping distance is 10m in plan and 20m vertical from the provided underground stope survey.
NSR is calculated from assay grades, metallurgical recovery, and the Net Smelter Price (“NSP”) using the formula:
NSR = (Cu%/100) x CAD$ 3.96/lb x 2204.6 lbs/tonne x 77% + Au gpt x CAD$76.05/g x 60%
These parameters assume a copper concentrate with gold credits as per the preliminary Metallurgical testing done in 2008 and 2010 and overseen by Gary Hawthorn, P.Eng.
A review of the drillhole data was undertaken and after statistical validation it was determined that the 1989 data was biased high for gold, low for silver and acceptable for interpolation of copper. Data from 1989 drillholes was considered in the development of the mineralization envelope but were not used in interpolations due to lack of certificates and QA/QC as well as the inability to have confidence in the 1989 grades. The model was run using the 1989 data only for copper.
Variography and Interpolations
The block model utilized a 10m x 10m x 5m selective mining unit with interpolation of copper and gold done using multiple passes of Inverse Distance Cubed with the variography as the basis of the interpolation search parameters. Variography found that within the mineralization the strongest correlation of assay values is trending at azimuth 160 dipping 40 degrees with a range of approximately 40 m.
Cumulative Probability Plots were used to establish gold and copper capping and outlier values. The table below summarizes the capping done on the assays prior to compositing and the Outlier Restrictions done to the composites during interpolation. For composite grades above the outlier value provided, and at distances greater than 5 m from the data, the value is essentially capped.
Specific Gravity and Resource Pit Limits
Specific Gravity (“SG”) is variable within the mineralization envelope, probably because of the presence of both lower SG dykes which are too thin to model and areas of higher SG sulfides and magnetite. SG was interpolated using 2 passes of Inverse Distance Squared interpolation using the same search parameters as Pass 3 and 4 of the gold/copper interpolation. SG values were capped at 4.6 prior to interpolation and any blocks not reached by the interpolation were assigned SG of 3.35 which is the median of the capped values.
Lerch Grossman pit optimization tools have been used to select a pit shape for limiting the resource. The LG pit targets NSR calculated in each block using copper and gold interpolation results.
The technical information contained in this news release has been prepared, reviewed, and approved by Wade Barnes, P.Geo. (BC), Coast Copper’s geological consultant and a Qualified Person (“QP”) within the context of Canadian Securities Administrators’ NI 43-101; Standards of Disclosure for Mineral Projects.
The 2023 MRE has been provided by Sue Bird, M Sc., P.Eng., Geological and Mining Engineer (NI 43-101 QP) of MMTS.
About Coast Copper Corp.
Coast Copper’s exploration focus is the optioned Empire Mine property, located on northern Vancouver Island, British Columbia, which covers three historical open pit mines and two past-producing underground mines that yielded iron, copper, gold and silver. Coast Copper’s other properties include its 100% owned Knob Hill NW Property located on northern Vancouver Island, its Home Brew and Shovelnose South Properties in central B.C., and its Scottie West Property located in the “Golden Triangle” of northern B.C. Coast Copper’s management team continues to review precious and base metals opportunities in western North America.
On Behalf of the Board of Directors:
Adam Travis, Chief Executive Officer and Director
For further information, please contact:
Adam Travis, CEO
Coast Copper Corp.
409 Granville Street, Suite 904
Vancouver, B.C. V6C 1T2, Canada
Cautionary Notes Related to this news release and/or map
1. The 2023 Mineral Resource Estimate was prepared by Sue Bird, P.Eng., an independent Qualified Person. The effective date of the mineral resource estimate is April 26, 2023. Mineral Resources are reported using the 2014 CIM Definition Standards and were estimated in accordance with the CIM 2019 Best Practices Guidelines, as required by NI43-101. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. There is no certainty that any Mineral Resources will be converted into Mineral Reserves. These Mineral Resource estimates include Inferred Mineral Resources that are considered too speculative geologically to have economic considerations applied to them that would enable them to be categorized as Mineral Reserves. It is reasonably expected that the majority of Inferred Mineral Resources could be upgraded to Measured or Indicated Mineral Resource with continued exploration. The Mineral Resource Estimate has been confined by a “reasonable prospects of eventual economic extraction” pit using the following assumptions, which were estimated from comparable projects:
a. Au price of USD$1,800/oz and Cu price of US$ 3.50/lb at an exchange rate of 0.75 US$ per CAD$;
b. 77% Cu metallurgical recovery, 29% Cu concentrate grade, 100$USD/tonne concentrate transport, 100 $USD/tonne concentrate treatment, 1% unit concentrate grade deduction, and 0.1 $USD/lb Cu refining cost
c. 60% Au metallurgical recovery, 99% payable Au, and 8 USD$/oz Au refining cost.
d. Mining costs of CAD$15/tonne;
e. Processing + G/A costs of CAD$25/tonne;
f. Pit slopes of 50 degrees;
The resulting NSR equation is: NSR (CDN$) = (Cu%/100) x 3.96 x 2204.6 x 0.77 + Au x 76.05 x 0.6. The bulk density of the deposit is interpolated from sample data. The average value specific gravity used for the Mineral Resource Estimate is 3.45 at the base case cutoff.
Copper and Gold Equivalents were calculated using CuEq=NSR/67.22 and AuEq=NSR/45.63, respectively.
2. A historical NI 43-101 Technical Report, authored by Giroux, G.H., & Raven, W. and dated November 30, 2008, concerning the copper gold resources for the Merry Widow Property was filed on Grand Portage Resources Ltd.'s SEDAR page on January 22, 2009. The 2008 Grand Portage historical resource estimate, completed by Gary H. Giroux, P.Eng, MASc, of Giroux Consulting Ltd., was based on a 3D geological model integrating 4,448 meters of diamond drilling of 43 drill holes, 2,290 assays, with 104 down-hole surveys collected between June and December 2006. The resource was reported utilizing gold cut-off grades ranging from 0.10 g/t to 3.00 g/t gold, as more particularly set out in the report. A complete copy of the report A gold cut-off grade of 0.50 g/t gold was selected as representing one possible mining scenario. For the purposes of the calculations, lognormal cumulative frequency plots were used to assess grade distribution to see if capping of high values was required and if so at what levels. For all elements, capping levels were established based on the individual grade distributions as follows: Gold - 18 gold assays were capped at 32.0 g/t gold, Silver - 9 silver assays were capped at 165 g/t silver, Copper - 7 assays were capped at 11.7% copper, Cobalt - 5 assays were capped at 0.48% cobalt, Iron - all iron assays were capped at 50% iron (the analytical detection limit).
3. Benson Lake Mine historical reserves recorded by Cominco Resources (1972) report a non NI 43-101 validated Measured and Indicated resource of 454,000 tonnes of 0.59 g/t Au and 1.3% Cu and Inferred resource of 2.7 million tonnes of 1.7% Cu with no Au grade calculated.
4. Cominco Resources, Drill Section Maps “Plan of Cominco’s Benson Lake Operations on Empire Claims Showing Ore Reserves & Proposed Exploration Program,” 1970, Private Files
Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING INFORMATION
Certain information contained or incorporated by reference in this press release, including any information regarding the proposed Transaction, private placement, board, and management changes, as to our strategy, projects, plans or future financial or operating performance, constitutes "forward-looking statements." All statements, other than statements of historical fact, are to be considered forward-looking statements. Forward-looking statements are necessarily based on a number of estimates and assumptions that, while considered reasonable by Coast Copper, are inherently subject to significant business, economic, geological, and competitive uncertainties, and contingencies. Although Coast Copper believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, such statements are not guarantees of future performance. Known and unknown factors could cause actual results to differ materially from those projected in the forward-looking statements. Such factors include but are not limited to fluctuations in market prices, exploration and exploitation successes, continued availability of capital and financing, changes in national and local government legislation, taxation, controls, regulations, expropriation, or nationalization of property and general political, economic, market or business conditions. Many of these uncertainties and contingencies can affect our actual results and could cause actual results to differ materially from those expressed or implied in any forward-looking statements made by, or on behalf of, us. Readers are cautioned that forward-looking statements are not guarantees of future performance and, therefore, readers are advised to rely on their own evaluation of such uncertainties. All of the forward-looking statements made in this press release, or incorporated by reference, are qualified by these cautionary statements. We do not assume any obligation to update any forward-looking statements.