Company Announcements

High grade interval in GS25-23 of 35m grading 0.97% Cu Eq. within 195.5m grading 0.42% Cu Eq.

Highlights:

• Recent drilling at West Goodspeed continues to confirm the presence of broad zones of copper-gold porphyry mineralization with locally higher-grade intervals, further supporting the potential for both near-surface and deeper higher-grade zones.
• Selected copper equivalent assay intercepts (based on Cu, Au, Mo and Re assays) include:
  • GS25-22: 18.0m grading 0.81% Cu Eq. from 21.0m within 30.0m grading 0.67% Cu Eq. from 13.0m, plus 14.0m grading 0.72% Cu Eq. from 61.0m within 30.0m grading 0.50% Cu Eq. from 53.0m
  • GS25-23: 35.0m grading 0.97% Cu Eq. from 224.5m within 195.5m grading 0.42% Cu Eq. from 64.0m
• Phase V drilling at the North Island Project commenced in August 2025 and is anticipated to include continued step-out drilling at West Goodspeed, extensive in-fill drilling and testing of regional targets across the property
• As of September 3, 2025, Northisle has completed a total of 10,046 metres of drilling: 6,903 metres in the West Goodspeed and Red Dog area, 2,132 metres across the Cougar, Goodspeed, and Northwest Expo targets, and 1,012 metres within the Red Dog open-pit footprint

VANCOUVER, British Columbia--(BUSINESS WIRE)--Sep. 8, 2025-- Northisle Copper and Gold Inc. (TSX-V: NCX, OTCQX: NTCPF) (“Northisle” or the “Company”) is pleased to announce additional results from its 2025 exploration campaign, comprised of six additional holes from the West Goodspeed target. These results continue to demonstrate wide intervals of mineralization near surface and contribute additional high-grade intervals at depth. Additional drilling during 2025 has been completed, testing areas to the northwest of West Goodspeed, and at other targets on the property.

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Figure 1: North Island Property Showing Location of Deposits and Prospects

Sam Lee, President and CEO stated, “We continue to be encouraged by the results to date from West Goodspeed. These results continue to demonstrate continuity of good grades and provided us the confidence to step out further to the northwest at West Goodspeed. We have confirmed mineralization over a corridor spanning more than 1,000m in strike length with only 50% of results received from exploration drilling in the West Goodspeed-Red Dog mineralized corridor.”

Discussion of Drill Results

Recent drilling at the West Goodspeed target continues to confirm the presence of a broad copper-gold porphyry system, with mineralization extending from near surface to depths exceeding 250 metres and over a strike length of at least 1,000 metres. The latest results highlight the potential for both shallow and deeper higher-grade zones, consistent with the current geological interpretation and previous drilling completed in 2024 (see Figures 2–4).

Of particular interest, hole GS25-23 intersected a broad zone of copper-gold mineralization, returning 195.5 metres grading 0.42% Cu Eq. from 64.0 metres depth, including a higher-grade interval of 35.0 metres grading 0.97% Cu Eq. from 224.5 metres. From the same drill pad but towards the northwest, hole GS25-24B returned 121.0 metres grading 0.28% Cu Eq. from 75.0 metres, including 27.0 metres grading 0.42% Cu Eq. from 147.0 metres.

These results are consistent with earlier intercepts in hole GS24-10 (see news release “Northisle Announces Additional Assays at West Goodspeed Confirm Near-Surface Copper-Gold Porphyry-style Mineralization Within Open Volume” dated August 19, 2024) and more recent results from GS25-17 and GS25-18 (see news release “Northisle Announces Near Surface Intercepts and Higher-Grade Intercepts at Depth at West Goodspeed on its North Island Project” dated July 2, 2025), collectively defining a robust mineralized corridor in this part of the target. The continuity in both grade and thickness supports the interpretation of this zone as one of the most prospective areas at West Goodspeed.

Hole GS25-22 returned multiple mineralized intervals that demonstrate both vertical and lateral continuity in the southeastern portion of the target. Near surface, the hole intersected 30.0 metres grading 0.67% Cu Eq. from 13.0 metres, including 18.0 metres grading 0.81% Cu Eq. from 21.0 metres. A second interval deeper in the hole returned 30.0 metres grading 0.50% Cu Eq. from 53.0 metres, including 14.0 metres grading 0.72% Cu Eq. from 61.0 metres. These results further confirm the continuity of shallow mineralization initially outlined by GS24-07 (also described in August 19, 2024, press release).

Hole GS25-21 also returned multiple intervals, including 28.0 metres grading 0.24% Cu Eq. from 80.0 metres, 18.0 metres grading 0.25% Cu Eq. from 144.0 metres, and a deeper interval of 51.0 metres grading 0.36% Cu Eq. from 237.0 metres. These results extend the mineralized system down-dip in this area, building on results from the initial discovery holes GS23-04 and GS23-05 reported in late 2023 (see news release “Northisle Makes New Discovery of Near Surface Copper-Gold Porphyry with multiple intercepts at West Goodspeed” dated December 6, 2023). In a similar manner, hole GS25-26 confirms the shallow mineralization zone outlined by GS23-04 and GS23-05, intersecting 104.0 metres grading 0.37% Cu Eq. from 61.0 metres, including a higher-grade interval of 20.0 metres grading 0.51% Cu Eq. from 91.0 metres. Jointly, GS25-21 and GS25-26, together with GS23-04 and GS23-05, define a mineralized area extending over 350 metres down-dip, which remains open in both down-dip and up-dip directions (see Figures 2–4).

Hole GS25-24B intersected 121.0 metres grading 0.28% Cu Eq., including 27.0 metres at 0.42% Cu Eq., confirming the extension down-dip of the upper part of the mineralization relative to GS25-23. Meanwhile, GS25-25 extends the deeper high-grade mineralization reported in GS25-18 (also highlighted in the company’s news release dated July 2, 2025) by approximately 100 metres to the southeast, returning 18.0 metres grading 0.89% Cu Eq. from 309.0 metres, within a broader interval of 75.0 metres grading 0.43% Cu Eq. from 276.0 metres. Collectively, holes GS25-18, GS25-23 and GS25-25 outline a higher-grade mineralized zone adjacent to the lower bounding fault, extending for approximately 220 metres in strike length and remaining open to the northwest (see Figures 2 and 4).

Together, these latest holes confirm the presence of a coherent mineralized system with both bulk-tonnage potential and discrete higher-grade domains. Ongoing interpretation will continue to refine the geometry and continuity of these higher-grade zones, with particular emphasis on the northwest portion of the target area.

To date, mineralization has been outlined over a strike length of more than 1km and extending about 250 metres down-dip from near surface. A total of 12 holes have been completed in the West Goodspeed area during 2025, with assays received for ten of them. An additional eight holes have been drilled along the projected mineralized trend toward the Red Dog area, northeast of the open-pit design, with assays pending.

Selected intervals from holes GS25-21 through GS25-26 are summarized in Table 1 below. Note that GS25-24A is not reported as it was terminated early due to unfavourable near-surface ground conditions. GS25-24B was collared from the same pad and progressed to the target depth.

Note on equivalent calculation for West Goodspeed:

Copper equivalent grade is determined by calculating total contained metal value per tonne, adjusted for recoveries, if known, dividing by the copper price, and then dividing the resultant number of pounds of copper by 2204.6. Gold equivalent grade is determined by calculating total contained metal value/tonne, adjusted for recoveries, if known, dividing by the gold price, and then multiplying the resultant number of troy ounces of gold by 31.103. Metal equivalent calculations are reported for illustrative purposes only and assumes 80% recoveries for the metals presented, based on comparable porphyry deposits, as metallurgical testing has not yet been completed on material from the West Goodspeed target.

Copper and gold equivalent calculations based on the following metal prices which were used in the Company’s 2025 Preliminary Economic Assessment for North Island: Cu = US$4.20/lb, Au = US$2,150/oz, Mo = US$21/lb, Re = US$1,950/kg. Intervals were selected based on continuous intercepts with a copper grade above 0.1% Cu or a gold grade above 0.1g/t Au. Totals may not add due to rounding.

Intervals are drill intersections and not necessarily true widths. True widths cannot be provided at this time due to the uncertainty in the geometry of the mineralization. Drill intersections have been selected and composites calculated independently by Northisle. The locations and distances highlighted on all maps in this news release are approximate.

Collar locations for the drill holes are detailed in Table 2. There are no material drilling, sampling, recovery, or other factors known that could materially affect the accuracy or reliability of the assay data.

Figure 1 shows a map of the overall North Island Project including existing deposits, key prospects and the focus area of this release.

Figure 2 shows the location of the drill holes announced in this press release in context with other drilling in the West Goodspeed area, while Figure 3 and Figure 4 show the drilling on a cross-section section highlighting results from GS25-21, GS25-23, GS25-24B, GS25-25, GS25-26 and surrounding holes.

Exploration at North Island Continues to Accelerate

The drill results described above are part of the Company’s broader 2025 exploration program which builds on the successful 2025 Preliminary Economic Assessment on the North Island Project which demonstrated an after-tax 29% IRR, $2 billion NPV and 1.9-year payback for a C$1.1 billion capex¹. The 2025 program includes:

• Expansion drilling at West Goodspeed and Red Dog area
• Advanced geophysical interpretation and soil geochemistry across the Northwest Corridor
• Regional stream sediment surveys and regional geophysical integration to define new potential areas of interest aiming to discover new porphyry mineralization centers over the full belt

As of September 3, 2025, Northisle has completed a total of 10,046 metres of drilling: 6,903 metres in the West Goodspeed and Red Dog area, 2,132 metres across the Cougar, Goodspeed, and Northwest Expo targets, and 1,012 metres within the Red Dog open-pit design sector.

After a short pause, in early August the Company commenced the fifth phase of drilling on the North Island Project. This program is anticipated to include continued step-out drilling at West Goodspeed, testing of additional targets on the property identified through the regional grassroots program, and extensive infill drilling at Northwest Expo, Red Dog, Hushamu and West Goodspeed with the goal of improving resource definition throughout the property.

Key 2025 milestones include the following:

• COMPLETED - Updated Preliminary Economic Assessment on North Island Project
• COMPLETED - 2025 Exploration Program Commenced
• COMPLETED - Initial results from drilling program at West Goodspeed
• COMPLETED - C$39.5 million financing
• COMPLETED - Commencement of Phase V exploration program
• COMPLETED - COO hired and additional team enhancements to support growth
• Q3 2025 - Results of belt-wide geophysical and geochemical data integration for the North Island Project
• Q3 2025 - Commencement of expanded baseline study program to support EA Readiness
• Q3 2025 - Initial results from Northwest Expo Area drilling aimed at discovering extensions of the high-grade gold mineralization at the Northwest Expo deposit
• Q4 2025 - Commence PFS-level metallurgical testing program
• Q4 2025 - Commence district-scale drilling program
• Ongoing - Continued positive engagement with indigenous rightsholders and local stakeholders
• Ongoing - Additional team additions to support further growth

Upcoming Investor Events

Northisle will be attending several external investor events including the following events:

• Fall 2025: Broker and Investor Site Visits
• September 9 - 12, 2025: Precious Metals Summit, Beaver Creek, CO
• September 14 - 17, 2025: Mining Forum Americas,Colorado Springs, CO
• October 6 - 10, 2025: Gentile European Tour in London, Paris, Zurich, Geneva, Frankfurt
• November 4 – 5, 20205: Red Cloud Fall Mining Showcase, Toronto, Canada
• November 19 - 21, 2025: Swiss Mining Institute, Zurich, Switzerland

Additional Technical Details

Logging, Sampling and Assaying Procedures and QA/QC

The diamond drill core logging and sampling program was carried out under a rigorous quality assurance / quality control (QA/QC) program. Drill intersections in this release are typically HQ to 150 metres and NQ thereafter to the end of holes. After drilling, core was logged for geology, structure, and geotechnical characteristics utilizing MX Deposit —core logging software, then marked for sampling and photographed on site. The cores for analyses were marked for sampling based on geological intervals with individual samples of 3-metre length or less. Drill core was cut lengthwise in half with a core saw. Half-core was sent for assays reported in this news release.

A total of +7% assay standards or blanks and +3% core duplicates are included in the sample stream as a quality control measure and are reviewed after analyses are received. Standards and Blanks were obtained from CDN Resource Laboratories, Langley, British Columbia. Blanks were obtained from unmineralized course bagged limestone landscaping rock. Standards and blanks in 2025 drill results to date have been approved as acceptable. Duplicate data add to the long-term estimates of precision for assay data on the project and precision for drill results reported is deemed to be within acceptable levels.

Samples were sent to the MSALABS in Langley, British Columbia, where the samples were dried, then crushed, split and a 250-gram (g) split was pulverized to 85% passing -200 mesh (-75 micrometres (µm)) size pulps. Clean crush material was passed through the crusher, and clean silica was pulverized between each sample. The pulps were analyzed for gold by fire assay fusion of 50 g of the 250 g split. Total gold content was determined by digesting the silver doré bead from the fusion and then analysing by AA (MSA Code FAS-121). All samples were also analyzed for multiple elements by taking a 0.25 g of the 250 g split which was heated in HNO3, HClO4 and HF to fuming and taken to dryness. The residue was dissolved in HCl and then analyzed utilizing ICP-MS (MSA Code IMS-230). Any sulphur analysis from this latter analysis with a value greater than 10% was reanalyzed utilizing a Leco sulfur analyzer. Iron and Tungsten accelerators are added to the sample and a stream of oxygen is passed over the sample in the induction furnace. As the sample is heated, sulfur dioxide released from the sample is measured by an IR detection system and the Total Sulphur content is determined. (MSA Code SPM-210). MSALABS (Langley) is an independent, international ISO/IEC 17025:2005 accredited laboratory.

Pulps and rejects of holes with significant assay intervals are stored at Western Mineral Storage. The remaining split core is indexed and stored at the Company’s logging and office facility in Port Hardy, BC.

Drill Results in this news release are length weighted averages.

Qualified Persons and Data Verification

Dr. Pablo Mejia Herrera, P.Geo., Vice President Exploration of Northisle and a Qualified Person as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects, has reviewed and approved the scientific and technical information contained in this news release. Dr. Mejia Herrera has verified the underlying data, including through multiple visits to drill sites, oversight of sample preparation protocols, and review of the QA/QC procedures applied to analytical results received from MSALABS.

About Northisle

Northisle Copper and Gold Inc. is a Vancouver-based company whose mission 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 economic potential of the project, and is now focused on accelerating the advancement of this compelling project while exploring within this highly prospective land package.

For more information on Northisle please visit the Company’s website at www.northisle.ca.

Cautionary Note Regarding Adjacent and Historical Property Disclosure

This news release contains information regarding adjacent and historical properties and deposits. Investors are cautioned that adjacent mineral deposits or systems, or past performance of historical mines, do not necessarily indicate and certainly do not prove the existence, nature or extent of mineral deposits on the North Island Project.

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 2025 exploration and development program, including the occurrence and expected timing of key milestones; plans and expectations regarding future project development; timing of key catalysts; planned activities, including further drilling, at the North Island Project; the Company’s anticipated exploration activities; 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; 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.

¹ Please see technical report titled “NI43-101 Technical Report and Preliminary Economic Assessment on North Island Project” (Effective Date: February 12, 2025) (“2025 PEA”) for more information. Readers are cautioned that the PEA is preliminary in nature and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as Mineral Reserves, and there is no certainty that the PEA will be realized.

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On behalf of Northisle Copper and Gold Inc.

Nicholas Van Dyk, CFA
Chief Financial Officer
Tel: (604) 335-3590
Email: info@northisle.ca
www.northisle.ca

Source: Northisle Copper and Gold Inc.