Northisle Copper and Gold Inc. announced preliminary metallurgical results from Northwest Expo which demonstrate combined flotation and leach recoveries for gold ranging from 88.7% to 92.6% and for copper from flotation ranging from 68.7% to 87.7%. 2024 Project Development Timeline: Upon completion of the initial Northwest Expo mineral resource estimate during First Quarter 2024, the company will review opportunities to optimize the North Island Project during Second Quarter 2024, including an evaluation of various combinations of the Northwest Expo, Red Dog and Hushamu deposits as standalone, combined or staged projects. Summary of Metallurgical Testing Procedures and Results: The test program was developed and managed by Ausenco Engineering Canada ULC (Ausenco) and K-met Consultants Inc. who are both independent of Northisle.

Base Metallurgical Laboratories Ltd. (BaseMet) performed the test work in Kamloops, BC and is also independent of Northisle. The core was first crushed to -6 mesh and prepared into master composite and variability test charges. A series of bench scale rougher and cleaner flotation tests were then conducted on the samples (2 and 4 kg test charges) at primary grind sizes ranging from 75 to 150m P80.

Flotation reagents used included 3418A, PAX and MIBC. The pH was varied from 6.6 to 11. Rougher concentrate regrind discharge sizes varied between 12 to 19m P80 prior to three stages of cleaner flotation.

Rougher and cleaner tails were both subsequently leached using sodium cyanide by bottle roll methods to maximize gold extraction. The copper grades were sufficiently low in both the rougher and flotation tails and did not impact leaching performance. The rougher tails were leached for 24 hours as the gold extraction appeared to complete.

The cleaner tails were pre-aerated with additional oxygen for 2 hours and subsequently leached for 48 hours, although the gold extraction was likely complete significantly earlier. Comminution tests were also performed with average Axb values of 84 and 67 for CMG and SCP samples, respectively. The average Bond ball mill work index was 16.9 kWh/t for all samples.

The samples have a lower resistance to breakage in a SAG mill than values measured on Hushamu and Red Dog samples, however the ball mill work index values are slightly higher. Data verification consisted of the Qualified Persons listed above (the "QPs") ensuring that the samples selected came from within the area which is likely to be included in Northisle's planned resource estimate, and that the selected samples are generally consistent with the mineralized material to be incorporated in that estimate. The QPs checked that the sampling protocol used by BaseMet was applicable for the planned testwork.

In the QPs' opinion, the testwork conducted was completed by a reputable metallurgical testing facility and used industry-standard methods. Peter Mehrfert, P.Eng., has visited the testwork facility. Internal QA/QC is performed by BaseMet as part of its testing protocols and Northisle has implemented QA/QC protocols for its drilling results as described further in Northisle's press release "Phase 2 Drilling at Northwest Expo Extends Strike of Gold-Enriched Zone 1 to 600m dated November 27, 2023.