Northisle Announces Significant Increase to North Island Resource Estimate

Contained Metal in Indicated Resources Increased to 10.1 billion lbs Cu Eq. or 16.2 million oz Au Eq. All dollar figures are C$ unless otherwise stated Highlights: Increased Indicated Resources by 330 million tonnes (+36%), adding 685 million lbs Cu (+22%) and 1.8 million oz Au (+26%) in contained metal 60% increase in contained Cu Eq. metal in Indicated Resources Exceeded resource objectives at West Goodspeed Addition of 113.1 million tonnes of Indicated Resources containing 873 million lbs Cu Eq. or 1.2 million oz Au Eq. Successful resource conversion at Northwest Expo and expansion of the resource along strike, which remains open to the northwest Contained Au in Indicated Resources increased 81% to 1.7 million oz Contained Cu in Indicated Resources increased 84% to 198 million lbs 30% increase in contained Cu Eq. metal in Indicated Resources at Red Dog with connection between Red Dog and West Goodspeed to be investigated with additional drilling in 2026 Additional critical minerals exposure with contained molybdenum in Indicated Resources increasing by 46% and contained rhenium in Indicated Resources increasing by 43% See below for further details Company Website: https://www.northisle.ca VANCOUVER, British Columbia -- (Business Wire) Northisle Copper and Gold Inc. (TSX-V: NCX, OTCQX: NTCPF) (“Northisle” or the “Company”) is pleased to announce the release of an integrated mineral resource estimate for its 100% owned North Island Project (the “2026 Resource Estimate”), which integrates the Northwest Expo, Red Dog, West Goodspeed, and Hushamu deposits. The 2026 Resource Estimate will be used for the development of a pre-feasibility study (“PFS”) on the North Island Project, which remains on target for completion in Q1 2027. This press release features multimedia. View the full release here: https://www.businesswire.com/news/home/20260806587703/en/ Figure 1: North Island Project Showing Location of Deposits and Prospects. Coordinates are reported in UTM Zone 9 North (NAD83 CRS, VD CVG28BC) with units in metres. Alex Davidson, Chairman, noted “This integrated resource update represents another important milestone for Northisle and is a critical step towards the completion of the North Island Project PFS. With 10.1 billion pounds of copper equivalent or 16.2 million ounces of gold equivalent contained in Indicated Resources, the 2026 Resource Estimate is finally beginning to tell the story of the district-scale potential of the North Island Project.” Sam Lee, President & CEO, stated “Over the past 18 months, we have either achieved or exceeded each of the goals we set in respect to resource growth and conversion. At West Goodspeed, we added over 113 million tonnes of Indicated Resources with 873 million lbs Cu Eq., or 1.2 million oz Au Eq. in contained metal. At Northwest Expo, we successfully converted Inferred material, increasing Indicated tonnage by 133%, and expanded the resource along strike. Significantly, at Red Dog, we increased contained copper equivalent metal in Indicated Resources by 30% and plan to investigate the connection between Red Dog and West Goodspeed with additional drilling in 2026. We additionally increased our exposure to critical minerals beyond copper, adding 68 million lbs Mo and 362,000 lbs Re in Indicated Resources. These results, in addition to improved commodity prices, have driven meaningful resource growth and provide a solid foundation for the North Island Project PFS, which remains on target for completion in Q1 2027.” The 2026 Resource Estimate contains an Indicated Resource of 1.2 billion tonnes grading 0.14% Cu, 0.22 g/t Au, 79.5 ppm Mo and 0.44 ppm Re for total contained metal of 10.1 billion lbs copper equivalent (“Cu Eq.”) or 16.2 million oz gold equivalent (“Au Eq.”) (recovery adjusted), plus an Inferred Resource of 260 million tonnes grading 0.12% Cu, 0.15 g/t Au, 62.0 ppm Mo, and 0.37 ppm Re for total contained metal of 1.5 billion lbs Cu Eq. or 2.6 million oz Au Eq. (recovery adjusted), at an $11.00/tonne NSR cut-off. Additionally, the 2026 Resource Estimate describes a shallow higher-grade portion of the Hushamu deposit (the “Hushamu Shallow Higher-Grade Core”), which is expected to be included in the first pushback to be extracted from the Hushamu deposit. In aggregate, the deposits comprising the Northwest Corridor, including Northwest Expo, Red Dog, and West Goodspeed, plus the Hushamu Shallow Higher-Grade Core, contain an Indicated Resource of 405 million tonnes grading 0.50% Cu Eq. or 0.46 g/t Au Eq. for total Indicated contained metal of 4.5 billion lbs Cu Eq. or 6.0 million oz Au Eq. The 2026 Resource Estimate has an effective date of July 31, 2026, and is summarized in Table 1 below by deposit. The 2026 Resource Estimate was prepared by Sue Bird, P.Eng. of Moose Mountain Technical Services (“MMTS”) who is independent of Northisle. Metallurgical test work which is referenced in the Design Basis (as defined below) was completed under the supervision of Peter Mehrfert, P.Eng. of Ausenco Engineering Canada ULC (“Ausenco”). A technical report (the “Technical Report”) prepared in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) will be filed on the Company’s website and SEDAR+ within 45 days of the date of this press release. Key assumptions reflected in the 2026 Resource Estimate are detailed below for each deposit and will be further described in the Technical Report. With the release of the 2026 Resource Estimate, the Company’s previous technical reports, including the 2025 North Island Project Preliminary Economic Assessment dated February 12, 2025, are no longer current and should not be relied upon. The $11.00/tonne NSR cut-off was selected as having reasonable prospects of eventual economic extraction as this value covers preliminary estimated Phase 2 processing and G&A costs as detailed in the Design Basis below. The economic assumptions presented may change during the completion of the ongoing North Island Project PFS.   Table 1: 2026 Integrated North Island Project Resource Estimate ($11.00 NSR cut-off)     Grade Contained Metal Tonnes Cu Au Mo Re Cu Eq. Au Eq. Cu Au Mo Re Cu Eq. Au Eq. NSR (000 T) (%) (g/t) (ppm) (ppm) (%) (g/t) (mm lbs) (000s oz) (mm lbs) (000 lbs) (mm lbs) (000s oz) ($/t) Indicated Northwest Expo 105,156   0.09 0.50 89.2 0.35 0.79 0.58   198 1,690 21 81 1,823 1,959   77.46 Red Dog 90,463   0.19 0.22 32.6 0.20 0.42 0.41   379 627 7 40 845 1,181   48.51 West Goodspeed 113,070   0.16 0.16 61.2 0.40 0.35 0.32   397 573 15 99 873 1,166   35.14 Hushamu 927,672   0.14 0.20 85.2 0.48 0.32 0.40   2,818 5,825 174 988 6,604 11,862   31.51 Total Indicated 1,236,361   0.14 0.22 79.5 0.44 0.37 0.41   3,793 8,715 217 1,209 10,145 16,168   36.99                                   Inferred                                   Northwest Expo 7,395   0.04 0.26 69.7 0.28 0.44 0.30   7 62 1 5 72 72   40.45 Red Dog 3,421   0.21 0.14 31.6 0.22 0.37 0.36   16 16 0 2 28 39   42.43 West Goodspeed 38,991   0.13 0.13 52.3 0.38 0.28 0.26   111 157 4 32 243 323   28.24 Hushamu 210,433   0.12 0.14 64.0 0.38 0.25 0.32   545 979 30 176 1,174 2,142   24.52 Total Inferred 260,240   0.12 0.15 62.0 0.37 0.26 0.31   678 1,214 36 214 1,517 2,576   25.77   Notes to the Resource Table: 1   Resources are reported using the 2014 CIM Definition Standards and were estimated using the 2019 CIM Best Practices Guidelines. 2   The Mineral Resources have been confined by an open pit with "reasonable prospects of eventual economic extraction" using the 125% revenue factor case and the following assumptions:     Metal prices of US$3,587/oz Au, US$4.82/lb Cu, US$20/lb Mo US$2,000/lb Re Forex of 1.32 $CDN:$US Payable metal of 97.5% payable Au, Payable of 96.5% for Cu, 99% payable Mo, and 50% payable Re Refining Costs of US$4.86/oz for Au, US$0.053/lb for Cu, US$0.95/lb for Mo, and US$0.60/lb for Re Smelting costs for Cu of US$53.20/dmt for Cu and US$98.80 for Mo Transportation and insurance costs of CDN$120/wmt proportionally distributed between Au, Cu and Mo Royalty of 1% NSR for Red Dog and West Goodspeed deposits Pit slopes are variable based on geotechnical zones and range from 31 degrees to 49 degrees, depending on sector Mining cost of US$3.00/t for waste and mineralized material Processing costs of CDN$10.30/t, general and administrative costs of CDN$0.70/t 3   Metallurgical recoveries for Au are: 91% for NW Expo, 84.5% for Red Dog, 78.2% for WGS and 59.2% for Hushamu in the CMG and 54.3% outside the CMG. 4   Metallurgical recoveries for Cu are variable at NW Expo and WGS as in Table 9.  At NW Expo averaging 73.8% and averaging 79.2% at WGS. Cu recovery is 89.7% at Red Dog and 77.8% at Hushamu within the CMG and 75.4% outside the CMG. 5   Metallurgical recoveries for Mo are 45.0% at NWExpo and Red Dog and variable at WGS with an average of 43.0%, and 49.2% at Hushamu within the CMG and 44.6% outside the CMG. 6   Metallurgical recoveries for Re are 36% at NWExpo and Red Dog and variable at WGS with an average of 34.5% at WGS, and 39.3% at Hushamu within the CMG and 35.7% outside the CMG. 7   The NSR equations are:      NW Expo within the CMG: NSR (CDN$/t)=(Au*91%*CDN$146.04g/t)+(Cu*CuRec%*CDN$5.98+Mo%*45%*CDN$24.63 + Re%*36%*CDN$1306)*2204.62 Red Dog: NSR (CDN$/t)=(Au*84.5%*CDN$141.34g/t) + (Cu*89.7%*CDN$5.79+Mo%*45%*CDN$24.39 + Re%*36%*CDN$1293)*2204.62 Hushamu within the CMG: NSR (CDN$/t)=((Au*59.2%*CDN$141.29g/t) + (Cu*77.8%*CDN$5.78 + Mo%*24.63*49.2% + Re%*CDN$1306*39.3%)*2204.62 Hushamu outside the CMG: NSR (CDN$/t)=((Au*54.3%*CDN$142.20g/t) + (Cu*75.4%*CDN$5.82 + Mo%*24.63*44.6% + Re%*CDN$1306*35.7%)*2204.62 WGS: NSR (CDN$/t)=(Au*78.2%*CDN$140.08g/t) + (Cu*CuRec%*CDN$5.74+Mo%*MoRec%*CDN$24.39 + Re%*ReRec%*CDN$1293)*2204.62 8   The Equivalent equations are: Cu Eq. = NSR/(Cu_NSP*Cu_Rec%*22.0462), Au Eq. = NSR/(Au_NSP*AuRec%) 9   The specific gravity for each deposit and domain ranges from 2.62-2.86 depending on alteration and is assumed to be 1.5 in overburden. 10   Numbers may not add due to rounding. Mineral resources are not mineral reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the mineral resources will be converted into mineral reserves. Inferred mineral resources are subject to uncertainty as to their existence and as to their economic and legal feasibility. The level of geological uncertainty associated with an inferred mineral resource is too high to apply relevant technical and economic factors likely to influence the prospects of economic extraction in a manner useful for evaluation of economic viability. 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. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. The Qualified Person(s) are of the opinion that issues relating to all relevant technical and economic factors likely to influence the prospects of eventual economic extraction can be resolved with further work. These factors may include environmental permitting, infrastructure, sociopolitical, marketing, or other relevant factors. Figure 1 shows the location of the deposits within the North Island Project in the context of regional infrastructure. Exploration and Development Milestones The Company continues to advance the North Island Project, with multiple near-term development and exploration catalysts including: COMPLETED – C$115 million financing to advance the North Island Project COMPLETED – Drilling results at Northwest Expo, extending strike and defining higher-grade zones COMPLETED – Commence extension drilling in Northwest Corridor COMPLETED – Initiate early engagement on mine waste storage area (ahead of schedule) COMPLETED – Drilling results at Red Dog, confirming additional higher-grade mineralization extending below the previous resource envelope COMPLETED – Integrated resource update for the North Island Project Q3 2026 – Initiate drilling at regional exploration targets H2 2026 – Initial Project Description filed H2 2026 – Commence BC Hydro System Impact Study H2 2026 – Results from ongoing drilling (Northwest Corridor and regional exploration) Q1 2027 – North Island Project PFS results announced Ongoing – Metallurgical test work (results to be included in North Island Project PFS) Ongoing –Continued positive engagement with indigenous rightsholders and local stakeholders Details of Northwest Expo Resource Estimate The Northwest Expo Resource Estimate includes a total of 61 diamond drill holes totalling 24,966 metres drilled by Northisle and previous operators through the end of 2025, of which 31 holes totalling 10,629 metres were completed under the direction of Northisle between 2024 and 2025. Table 2 below summarizes the Northwest Expo Resource Estimate and shows the sensitivity of the estimate to cut-off assumptions.   Table 2: 2026 Northwest Expo Resource Estimate   In Situ Grade Contained Metal NSR Cutoff ($/T) Resource Class Tonnes (000 T) NSR ($/t) Cu (%) Au (g/t) Mo (ppm) Re (ppm) Cu Eq. (%) Au Eq. (g/t)   Cu (mm lbs) Au (000s oz) Mo (mm lbs) Re (000 lbs) Cu Eq. (mm lbs) Au Eq. (000s oz) Strip Ratio $10.00 Indicated 106,083 76.87 0.08 0.50 89.03 0.35 0.78 0.58   199 1,692 21 82 1,826 1,962 3.65 Inferred 7,525 39.93 0.04 0.26 69.07 0.28 0.44 0.30   7 62 1 5 73 72 $11.00 Indicated 105,156 77.46 0.09 0.50 89.20 0.35 0.79 0.58   198 1,690 21 81 1,823 1,959 3.69 Inferred 7,395 40.45 0.04 0.26 69.65 0.28 0.44 0.30   7 62 1 5 72 72 $15.00 Indicated 99,721 80.96 0.09 0.52 88.82 0.35 0.82 0.61   197 1,676 20 76 1,801 1,942 3.96 Inferred 6,818 42.78 0.04 0.28 71.17 0.29 0.47 0.32   6 61 1 4 70 70 $20.00 Indicated 90,586 87.36 0.10 0.57 84.88 0.33 0.88 0.65   196 1,647 17 66 1,754 1,904 4.48 Inferred 5,738 47.45 0.05 0.31 70.80 0.28 0.51 0.36   6 57 1 4 65 65 Refer to Table 1 for Notes to the Resource Table. Figure 2 shows the resource pit shell and modelled block grades for the Northwest Expo deposit showing the NSR blocks above the $11.00/tonne cut-off. Details of Red Dog Resource Estimate The Red Dog Resource Estimate includes a total of 96 diamond drill holes totalling 21,970 metres drilled by Northisle and previous operators through the end of April 2026, of which 47 holes totalling 12,315 metres of assaying were completed under the direction of Northisle between June 2025 and April 2026. Table 3 below summarizes the Red Dog Resource Estimate and shows the sensitivity of the estimate to cut-off assumptions.   Table 3: 2026 Red Dog Resource Estimate   In Situ Grade Contained Metal NSR Cutoff ($/T) Resource Class Tonnes (000 T) NSR ($/t) Cu (%) Au (g/t) Mo (ppm) Re (ppm) Cu Eq. (%) Au Eq. (g/t)   Cu (mm lbs) Au (000s oz) Mo (mm lbs) Re (000 lbs) Cu Eq. (mm lbs) Au Eq. (000s oz) Strip Ratio $10.00 Indicated 90,961 48.30 0.19 0.21 32.51 0.20 0.42 0.40   380 628 7 40 846 1,183 2.26 Inferred 3,476 41.93 0.21 0.14 31.28 0.22 0.37 0.35   16 16 0 2 28 39 $11.00 Indicated 90,463 48.51 0.19 0.22 32.64 0.20 0.42 0.41   379 627 7 40 845 1,181 2.28 Inferred 3,421 42.43 0.21 0.14 31.59 0.22 0.37 0.36   16 16 0 2 28 39 $15.00 Indicated 87,802 49.58 0.19 0.22 33.25 0.20 0.43 0.42   376 622 6 39 839 1,172 2.39 Inferred 3,219 44.27 0.22 0.15 32.48 0.23 0.39 0.37   16 15 0 2 27 38 $20.00 Indicated 82,720 51.54 0.20 0.23 34.14 0.21 0.45 0.43   368 610 6 38 821 1,148 2.60 Inferred 2,799 48.26 0.24 0.16 31.99 0.22 0.42 0.40   15 15 0 1 26 36 Refer to Table 1 for Notes to the Resource Table. Table 4 below summarizes the shallow higher-grade core of the Red Dog deposit that is expected to be included in the first pushback of mining from Red Dog. This pit shell is defined by the 30% revenue factor of the base case economic inputs defining the resource pit shell.   Table 4: Red Dog Shallow Higher-Grade Core   In Situ Grade Contained Metal Resource Class Tonnes (000 T) NSR ($/t) Cu (%) Au (g/t) Mo (ppm) Re (ppm) Cu Eq. (%) Au Eq. (g/t)   Cu (mm lbs) Au (000s oz) Cu Eq. (mm lbs) Strip Ratio Indicated 26,579 70.50 0.25 0.34 50.34 0.30 0.62 0.59   144 293 361 0.11 Inferred 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00   0 0 0 Refer to Table 1 for Notes to the Resource Table. Figure 3 shows the resource pit shell (grey) and the low strip-ratio, higher-grade conceptual initial phase (gold) as summarized above. The modelled block grades shown are the NSR blocks above the $11.00/tonne cut-off. Details of West Goodspeed Resource Estimate The West Goodspeed Resource Estimate includes a total of 47 diamond drill holes totalling 14,435 metres drilled by Northisle and previous operators through the end of August 2025, of which 38 holes totalling 12,000 metres were completed under the direction of Northisle between 2023 and 2025. Table 5 below summarizes the West Goodspeed Resource Estimate and shows the sensitivity of the estimate to cut-off assumptions.   Table 5: 2026 West Goodspeed Resource Estimate   In Situ Grade Contained Metal NSR Cutoff ($/T) Resource Class Tonnes (000 T) NSR ($/t) Cu (%) Au (g/t) Mo (ppm) Re (ppm) Cu Eq. (%) Au Eq. (g/t)   Cu (mm lbs) Au (000s oz) Mo (mm lbs) Re (000 lbs) Cu Eq. (mm lbs) Au Eq. (000s oz) Strip Ratio $10.00 Indicated 114,345 34.86 0.16 0.16 60.77 0.40 0.35 0.32   398 574 15 100 876 1,170 1.67 Inferred 39,542 27.99 0.13 0.12 51.85 0.37 0.28 0.26   111 158 5 33 244 325 $11.00 Indicated 113,070 35.14 0.16 0.16 61.22 0.40 0.35 0.32   397 573 15 99 873 1,166 1.71 Inferred 38,991 28.24 0.13 0.13 52.28 0.38 0.28 0.26   111 157 4 32 243 323 $15.00 Indicated 107,136 36.35 0.16 0.16 62.98 0.41 0.36 0.33   388 563 15 97 855 1,143 1.87 Inferred 36,077 29.45 0.13 0.13 54.20 0.39 0.29 0.27   106 152 4 31 234 312 $20.00 Indicated 93,125 39.16 0.18 0.18 66.73 0.43 0.39 0.36   362 529 14 89 801 1,070 2.35 Inferred 29,551 32.03 0.14 0.15 58.13 0.42 0.32 0.29   93 139 4 27 208 278 Refer to Table 1 for Notes to the Resource Table. Figure 4 shows the resource pit shell and modelled block grades for the West Goodspeed deposit showing the NSR blocks above the $11.00/tonne cut-off. Details of Hushamu Resource Estimate The Hushamu Resource Estimate includes a total of 165 diamond drill holes totalling 40,482 metres drilled by Northisle and previous operators through the end of 2022, of which 40 holes totalling 13,345 metres of assaying were completed under the direction of Northisle between 2011 and 2023. Table 6 below summarizes the Hushamu Resource Estimate and shows the sensitivity of the estimate to cut-off assumptions.   Table 6: 2026 Hushamu Resource Estimate   In Situ Grade Contained Metal NSR Cutoff ($/T) Resource Class Tonnes (000 T) NSR ($/t) Cu (%) Au (g/t) Mo (ppm) Re (ppm) Cu Eq. (%) Au Eq. (g/t)   Cu (mm lbs) Au (000s oz) Mo (mm lbs) Re (000 lbs) Cu Eq. (mm lbs) Au Eq. (000s oz) Strip Ratio $10.00 Indicated 942,630 31.17 0.14 0.19 85.03 0.48 0.32 0.39   2,828 5,858 177 1,001 6,640 11,926 0.44 Inferred 213,047 24.35 0.12 0.14 63.73 0.38 0.25 0.31   548 984 30 177 1,181 2,154 $11.00 Indicated 927,672 31.51 0.14 0.20 85.22 0.48 0.32 0.40   2,818 5,825 174 988 6,604 11,862 0.47 Inferred 210,433 24.52 0.12 0.14 64.04 0.38 0.25 0.32   545 979 30 176 1,174 2,142 $15.00 Indicated 848,172 33.23 0.15 0.21 86.11 0.49 0.34 0.42   2,741 5,607 161 914 6,367 11,429 0.60 Inferred 195,532 25.38 0.12 0.15 65.42 0.39 0.26 0.33   522 947 28 167 1,129 2,060 $20.00 Indicated 702,991 36.46 0.16 0.22 87.19 0.50 0.37 0.46   2,534 5,072 135 769 5,786 10,372 0.96 Inferred 147,938 27.88 0.13 0.17 67.76 0.41 0.29 0.36   433 796 22 133 938 1,711 Refer to Table 1 for Notes to the Resource Table. Table 7 below highlights the shallow higher-grade core of the Hushamu deposit that is expected be included in the first pushback to be extracted from this deposit. This pit shell is defined by the 37% revenue factor of the base case economic inputs defining the resource pit shell.   Table 7: Hushamu Shallow Higher-Grade Core   In Situ Grade Contained Metal Resource Class Tonnes (000 T) NSR ($/t) Cu (%) Au (g/t) Mo (ppm) Re (ppm) Cu Eq. (%) Au Eq. (g/t)   Cu (mm lbs) Au (000s oz) Cu Eq. (mm lbs) Strip Ratio Indicated 96,439 44.06 0.21 0.26 79.22 0.44 0.45 0.54   447 801 953 0.40 Inferred 2,094 39.28 0.16 0.26 84.93 0.65 0.40 0.49   7 17 18 Refer to Table 1 for Notes to the Resource Table. Figure 5 shows the resource pit shell (grey) and the higher-grade, 37% conceptual pit shell (gold) as summarized above. The modelled block grades shown are the NSR blocks above the $11.00/tonne cut-off. Design Basis The following Design Basis was established for the purpose of the 2026 Resource Estimate. The economic assumptions presented here may change during the completion of the ongoing North Island Project PFS.   Table 8: Design Basis Key Assumptions   Assumption Units Quantity Copper Price US$/lb $4.82 Gold Price US$/oz $3,587 Molybdenum Price US$/lb $20.00 Rhenium Price US$/lb $2,000 Foreign Exchange C$/US$ 1.32 Concentrate Moisture % 9% Copper Concentrate Treatment Charge US$/DMT $53.20 Copper Payable % 96.5% Gold Payable % 97.5% Copper Refining Charge US$/lb $0.053 Gold Refining Charge US$/oz $4.86 Molybdenum Concentrate Treatment Charge US$/DMT $98.80 Molybdenum Payable % 99.0% Rhenium Payable % 50.0% Molybdenum Refining Charge US$/lb $0.95 Rhenium Refining Charge US$/lb $0.60 Concentrate Transport Charge $/WMT $120.00 NSR Royalty – NW Expo and Hushamu % 0% NSR Royalty – Red Dog and West Goodspeed % 1%* Processing and G&A Cost $/T $11.00 * Assumes repurchase of 2% of the outstanding 3% NSR for $2 million.   Table 9: Metallurgical Recoveries and Concentrate Grades     Northwest Expo Red Dog West Goodspeed Hushamu CMG Hushamu SCP Cu Process Recovery 73.8%1 89.7% 79.2%1 77.8% 75.4% Au Process Recovery 91.0% 84.5% 78.2% 59.2% 54.3% Cu Concentrate Cu Grade 22% 22% 22% 22% 22% Au Concentrate Grade (g/t) 93 20 12 11 16 Mo Process Recovery 45.0% 45.0% 43.0%1 49.2% 44.6% Re Process Recovery 36.0% 36.0% 34.5%1 39.3% 35.7% Mo Concentrate Mo Grade 50.0% 50.0% 50.0% 50.0% 50.0% Notes: 1.   Recoveries are variable. Figures shown are averages based on the following formulas:     NWE Cu Process Recovery: (90+6.5*ln(Cu%))/100 WGS Cu Process Recovery: (78.4+5.1*(Cu%))/100 WGS Mo Process Recovery: (ln(Mo ppm)*7.6+12)/100 WGS Re Process Recovery: (ln(Mo ppm)*6.1+9.6)/100 Details of Metallurgical Testing Procedures and Results The Design Basis is informed by the results of the same metallurgical testing programs that supported the 2025 Preliminary Economic Assessment for the North Island Project (the “2025 PEA”). In connection with the 2025 PEA, Peter Mehrfert, P.Eng., (Ausenco) reviewed and interpreted several metallurgical test programs conducted under the direction of Northisle since 2009. The test programs utilized half drill core samples and were conducted at three metallurgical testing laboratories: ALS Metallurgy (Kamloops, BC), Base Metallurgical (Kamloops, BC) and SGS (Lakefield, ON). Molybdenum recoveries for Northwest Expo and Red Dog were not previously considered for the 2025 PEA; recovery of this metal is now estimated based on testing conducted prior to 2025. Copper recovery for NW Expo was previously estimated as constant values in the 2025 PEA, a variable Cu recovery was applied to conservatively estimate recoveries on lower grade materials. West Goodspeed drill core samples were tested at Base Metallurgical, starting in 2025. Recoveries for this deposit are estimated based on preliminary results measured on 9 variability samples and one master composite. Copper-molybdenum separation testing has not yet been completed on samples from any of the deposits. It is assumed that this circuit will recover 90% of the molybdenum contained in the bulk Cu-Mo concentrates and can produce a 50% molybdenum concentrate grade. Both metallurgical performance targets are typical of Cu-Mo separation circuits. Rhenium recovery to a marketable molybdenum concentrate has also not yet been measured. It is estimated that rhenium recovery to the molybdenum concentrate will be 80% of the predicted molybdenum recovery, as this metal typically occurs as a molybdenum substitute in molybdenite. Additional metallurgical testing programs to support the North Island Project PFS (the “PFS Metallurgical Testing Programs”) are ongoing, with results to be incorporated into the North Island Project PFS. The PFS Metallurgical Testing Programs may yield different results than prior metallurgical testing programs, and Mr. Mehrfert’s review and interpretation of the PFS Metallurgical Testing Programs may result in changes to the Design Basis during the completion of the ongoing North Island Project PFS. Additional Technical Details Details of Resource Estimation Methodology At each deposit, three-dimensional solids have been created of the alteration / lithologies to aid in the orientation and extent of the mineralized domains used to confine the resource grade interpolations. Cumulative probability plots are used to define capping values of the assays and potential outlier restrictions of the composites during interpolations. Compositing has been done by three metre intervals honoring the domain boundary for each element. Three meters was selected because it is the length of the longest assays. Values less than 1.5m have been added to the composite above to avoid small composite lengths. Ordinary Kriging interpolations have been used for Au, Cu, Mo and Re interpolations. Search distances and orientations for each metal are based on the variography and will be fully described in the supporting technical report. Resource classification is based on the distance between drillholes with criteria based on the variography using the following process. All blocks interpolated with at least a Cu grade are initially classified as Inferred. Blocks are upgraded to Indicated using the criteria summarized in the following table:   Table 10: Summary of Resource Classification Criteria   Deposit Hushamu NW Expo Red Dog WGS   Domain 1 Domain 1 Domain 1 Domain 2 Domain 1 Average Distance to 2 DHs 250 na na na na Average Distance to 3 DHs na 100 60 150 100 Maximum distance to DH 350 360 85 212 140 The classification was adjusted to reduce extrapolation and to ensure continuity as follows: At Northwest Expo, blocks were then examined and those near surface were downgraded to Inferred due to lack of near-surface drilling and extrapolation in this area. A small number of blocks of isolated Indicated were downgraded to Inferred and of isolated Inferred upgraded to Indicated. The modelled tonnage and grades have been validated by comparison of the average grades with the de-clustered composite data and using swath plots, grade-tonnage curves and visual validations on section and in plan. Additional details on the methodology will be provided in the Technical Report relating to the 2026 Resource Estimate. Qualified Persons and Data Verification Sue Bird, P. Eng, V.P. of MMTS, and a Qualified Person as defined by NI 43-101, has reviewed and approved the scientific and technical disclosure contained in this news release relating to the 2026 Resource Estimate. Ms. Bird has verified the data incorporated in the 2026 Resource Estimate by certificate checks, standards, blank and duplicate plots. Ms. Bird experienced no limitations with respect to data verification activities related to the North Island Project. The information in this press release relating to the metallurgical test work results has been reviewed and verified by Peter Mehrfert, P.Eng., (Ausenco). Mr. Mehrfert is a Qualified Person under NI 43-101. Mr. Mehrfert has verified the metallurgical recoveries incorporated in the 2026 Resource Estimate by reviewing the test data and the laboratory’s QA/QC protocols. Mr. Mehrfert experienced no limitations with respect to data verification activities related to the North Island Project. Dr. Pablo Mejia Herrera, P.Geo., Vice President Exploration of Northisle, and a Qualified Person as defined by NI 43-101, has reviewed and approved all other scientific and technical disclosure contained in this news release. About Northisle Northisle Copper and Gold Inc. is a Vancouver-based company whose vision is to become Canada’s leading sustainable mineral resource company for the future. Northisle, through its 100% owned subsidiary North Island Mining Corp., owns the North Island Project, which is one of the most promising copper and gold porphyry projects in Canada. The North Island Project is located near Port Hardy, British Columbia on a more than 34,000-hectare block of mineral titles 100% owned by Northisle on a belt stretching 50 kilometres northwest from the now closed Island Copper Mine operated by BHP Billiton. Since 2021, the Company has discovered two significant deposits, expanded resources, demonstrated the potential of the North Island Project, and is now focused on the development of this compelling project while exploring within this highly prospective land package. Northisle respectfully acknowledges that our North Island Project is located within the territories of Quatsino First Nation, Kwakiutl First Nation, and Tlatlasikwala First Nation. We are committed to collaborating with First Nations to build authentic, mutually beneficial relationships. For more information on Northisle please visit the Company’s website at www.northisle.ca. Cautionary Statements regarding Forward-Looking Information Certain information in this news release constitutes forward-looking statements under applicable securities law. Any statements that are contained in this news release that are not statements of historical fact may be deemed to be forward-looking statements. Forward-looking statements are often identified by terms such as “may”, “should”, “anticipate”, “expect”, “intend” and similar expressions. Forward-looking statements in this news release include, but are not limited to: plans and expectations regarding the 2026 exploration program; plans and expectations regarding future project development; timing of key catalysts; planned activities, including further drilling, at the North Island Project and the North Island Pre-feasibility Study; anticipated impact of drilling results from West Goodspeed, Northwest Expo, Red Dog and other targets on Mineral Resource Estimates; the Company’s anticipated exploration activities; the timing of the filing of the Technical Report in respect of the 2026 Resource Estimate; the timing, completion and results of the Pre-feasibility Study; the Design Basis and economic assumptions, including the NSR cut-off grade, used in the 2026 Resource Estimate, and the possibility that such assumptions may change during the completion of the Pre-feasibility Study; the timing, scope and results of the PFS Metallurgical Testing Programs and the Company’s plans for advancement of the North Island Project. Forward-looking statements necessarily involve known and unknown risks, including, without limitation, the Company’s ability to implement its business strategies; risks associated with mineral exploration and production; risks associated with general economic conditions; adverse industry events; stakeholder engagement; marketing and transportation costs; loss of markets; volatility of commodity prices; inability to access sufficient capital from internal and external sources, and/or inability to access sufficient capital on favourable terms; industry and government regulation; changes in legislation, income tax and regulatory matters; competition; currency and interest rate fluctuations; risks that the Technical Report is not filed within the timeline anticipated; risks that the results of the PFS Metallurgical Testing Programs differ from prior metallurgical test results and require changes to the Design Basis and the economic assumptions underlying the 2026 Resource Estimate; risks that the anticipated repurchase of a portion of the outstanding NSR royalty on the Red Dog and West Goodspeed deposits is not completed on the terms anticipated or at all; risks relating to permitting and regulatory approval timelines, including in respect of the BC Hydro System Impact Study and the Initial Project Description and other risks. Readers are cautioned that the foregoing list is not exhaustive. Readers are further cautioned not to place undue reliance on forward-looking statements as there can be no assurance that the plans, intentions, or expectations upon which they are placed will occur. Such information, although considered reasonable by management at the time of preparation, may prove to be incorrect and actual results may differ materially from those anticipated. Forward-looking statements contained in this news release are expressly qualified by this cautionary statement. The forward-looking statements contained in this news release represent the expectations of management of Northisle as of the date of this news release, and, accordingly, are subject to change after such date. Northisle does not undertake any obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as expressly required by applicable securities law. 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 news release. View source version on businesswire.com: https://www.businesswire.com/news/home/20260806587703/en/ Contacts: On behalf of Northisle Copper and Gold Inc. Nicholas Van Dyk, CFA Chief Financial Officer Tel: (604) 638-2515 Email: [email protected] www.northisle.ca Source: Northisle Copper and Gold Inc.