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All financial quantities in C$

Corporate Updates

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

All financial quantities in C$ unless otherwise noted.

October 10, 2024

TSX Venture Exchange Symbol: NCX

Northisle Announces North Island Project Indicated Resource Estimate Increased to 3.1

billion lbs Cu and 6.9 million ozs Au

Highlights:

• Integrated North Island Project resource estimate demonstrates a 60% increase in global Indicated tonnage to

906 million tonnes containing 3.1 billion lbs Cu, 6.9 million ozs Au, 149 million lbs Mo and 847,000 lbs Re

o 27% increase in contained Cu, 41% increase in contained Au, 69% increase in contained Mo and 132%

increase in contained Re in the Indicated category compared to previous estimates

• Additional Inferred resource estimate of 214 million tonnes containing 571 million lbs Cu, 1.5 million ozs Au, 24

million lbs Mo and 147,000 lbs Re

• Modelled strip ratio improved to 0.70:1 waste to above cut-off mineralization property wide

• Resource Estimate will be incorporated in an updated PEA which will consider a two-phase development of the

North Island Project

Vancouver, B.C. – Northisle Copper and Gold Inc. (TSX-V: NCX) (“Northisle” or the “Company”) is pleased to announce

the release of an integrated resource estimate for its 100% owned North Island Project (the “Resource Estimate”) which

integrates the Hushamu, Red Dog and Northwest Expo deposits. The Resource Estimate will be used for the

development of an updated preliminary economic assessment (“PEA”) on the North Island Project which is now

anticipated in early Q1 2025.

Sam Lee, President & CEO of Northisle stated “We have reached yet another milestone at the North Island Project with

the updated global resource which is a culmination of our focused exploration program over the past four years. The

project now boasts over 3 billion pounds of copper and nearly 7 million ounces of gold in Indicated resources, making it

one of the largest copper and gold porphyries in Canada not currently owned by a major. These results form the basis

for the completion of the new PEA on the North Island Project and allow us to contemplate a phased project with lower

initial capital intensity that can bridge to a potentially larger project and longer life of mine.”

The updated Resource Estimate contains an Indicated Resource of 906 million tonnes grading 0.16% Cu and 0.24g/t Au,

75 ppm Mo and 0.42ppm Re, for total contained metal of 6.3 billion lbs Cu Eq. (recovery adjusted), plus an additional

214 million tonnes Inferred Resource grading 0.12% Cu, 0.22g/t Au, 52ppm Mo and 0.31ppm Re for 1.3 billion lbs Cu Eq.

(recovery adjusted), at an $11.50/tonne NSR cut-off.

The Resource Estimate is summarized in Table 1 below. The 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 prepared in accordance with NI43-101 (the “Technical

Report”) 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 Resource Estimate are detailed below for each deposit and will be further described in

the Technical Report. With the release of the Resource Estimate, the Company’s previous technical reports, including the

Amended 2021 North Island Copper and Gold Project Preliminary Economic Assessment filed June 2022 are no longer

current and should not be relied upon.

The $11.50/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.

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

Table 1: 2024 Integrated North Island Project Resource Estimate ($11.50 NSR cut-off)

Grade Contained Metal NSR

Tonnes Cu Au Mo Re Cu Eq. Cu Au Mo Re Cu Eq. ($/T)

(000 T) (%) (g/t) (ppm) (ppm) % mm lbs 000s oz mm lbs 000 lbs mm lbs

Indicated

Hushamu 777,749 0.16% 0.21 87 0.49 0.29% 2,663 5,326 149 847 5,034 23.00

Red Dog 83,129 0.18% 0.25 n/a n/a 0.35% 336 679 0 0 650 33.14

Northwest Expo 45,044 0.11% 0.64 n/a n/a 0.65% 108 933 0 0 646 54.15

Total Indicated 905,922 0.16% 0.24 75 0.42 0.31% 3,107 6,939 149 847 6,330 25.48

Inferred

Hushamu 168,459 0.13% 0.16 66 0.40 0.23% 472 860 24 147 852 17.77

Red Dog 9,808 0.14% 0.18 n/a n/a 0.26% 30 56 0 0 56 24.18

Northwest Expo 35,611 0.09% 0.53 n/a n/a 0.53% 69 609 0 0 412 44.88

Total Inferred 213,878 0.12% 0.22 52 0.31 0.28% 571 1,525 24 147 1,320 22.58

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 effective date of the Resource Estimate is September 23, 2024.

3. The Mineral Resources have been confined by open pits with "reasonable prospects of eventual economic extraction" using the 125% pit case and the

assumptions outlined in the Design Basis in Table 4 and the metallurgical recoveries in Table 5 below.

4. The NSR is calculated as follows:

• Hushamu chlorite-magnetite-silica altered mineralization (“CMG”):

NSR($/t)=(Cu(%)*77.8%*$4.72*2204.62)+(Au(gpt)*59%*$70.35/g)+(Mo(%)*49%*$25.32*2204.62)+(Re(%)*39.3%*$530.29*2204.6)

• Hushamu non-CMG (based on silica-clay-pyrite (“SCP”) and applied to all other domains):

NSR(C$/t)=(Cu(%)*75.4%*$4.70*2204.62)+(Au(gpt)*54%*$70.01/g)+(Mo(%)*45%*$25.32*2204.62)+(Re(%)*35.7%*$530.29*2204.6)

• Northwest Expo CMG: NSR($/t)=(Cu(%)*73%*$4.89*2204.62)+(Au(gpt)*91%*$76.85/g)

• Northwest Expo non-CMG: NSR($/t)=(Cu(%)*88%*$4.91*2204.62)+(Au(gpt)*91%*$77.06/g)

• Red Dog: NSR($/t)=(Cu(%)*89.7%*$4.72*2204.62)+(Au(gpt)*85%*$74.08/g)

5. Copper Equivalents are calculated as follows, which reflect the differences in recoveries, payables and metal prices between the deposits:

• Northwest Expo CMG: Cu Eq. = Cu + Au*0.888; Non-CMG: Cu Eq. = Cu + Au*0.737

• Red Dog: Cu Eq. = Cu + Au*0.675

• Hushamu CMG: Cu Eq. = Cu + Au*0.512 + Mo*0.00034 + Re*0.00567; Non-CMG: Cu Eq. = Cu + Au*0.484 + Mo*0.00032 + Re*0.00534

6. Gold Equivalent for Northwest Expo is calculated as follows: CMG: Au Eq. = Au + 1.126*Cu%; Non-CMG Au Eq. = Au + 1.358*Cu%

7. 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

8. The combined Resource Estimate incorporates a strip ratio of approximately 0.7:1 waste to above cut-off mineralization

9. Amounts may not add due to rounding

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.

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

Figure 1: North Island Project Showing Deposit and Target Locations

2024 Catalysts

The Company continues to advance the North Island Project, with multiple development and exploration catalysts

leading to measurable impacts for shareholders including the following:

• COMPLETED - Geophysics results from Northwest Expo and West Goodspeed

• COMPLETED - Northwest Expo metallurgical testing and initial resource estimate

• COMPLETED - Final 2023 Pemberton Hills Drill Results

• COMPLETED - Commencement of 2024 drilling program

• COMPLETED - Preliminary Project Trade-offs

• COMPLETED - Commencement of advanced economic and technical studies

• COMPLETED - Initial drill results from West Goodspeed

• COMPLETED - Integrated North Island Project Mineral Resource Estimate Update

• Early Q4 2024 - Additional West Goodspeed Exploration Results

• Q4 2024 – Northwest Expo Exploration Results

• Early Q1 2025 - North Island Project 2024 PEA

• Q1 2025 – Final 2024 West Goodspeed Exploration Results

• Ongoing - Continued positive engagement with indigenous rightsholders and local stakeholders

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

Details of Hushamu Resource Estimate

The Hushamu Resource Estimate includes a total of 162 diamond drill holes totalling 40,468 meters drilled by Northisle

and previous operators through the end of 2023, of which 30 holes totalling 13,791 meters were completed under the

direction of Northisle between 2011 and 2023.

Table 2 below summarizes the Hushamu Resource Estimate and shows the sensitivity of the estimate to cut-off

assumptions.

Table 2: 2024 Hushamu Mineral Resource Estimate

NSR

Cutoff Class

In Situ Tonnage and Grade Cu

Metal

mm

lbs

Au

Metal

000s

oz

Mo

Metal

mm

lbs

Re

Metal

000s

lbs

Cu Eq.

Metal

mm

lbs

Strip Tonnage Cu Au Mo Re Cu Eq. NSR

($/T) (000 T) (%) (gpt) (ppm) (ppm) (%) ($/t) Ratio

$10.00 Indicated

Inferred

837,870 0.15 0.21 87 0.49 0.28 $22.12 2,736 5,544 160 908 5,218 0.44 187,107 0.12 0.15 66 0.39 0.22 $17.09 502 912 27 161 910

$11.50 Indicated

Inferred

777,749 0.16 0.21 87 0.49 0.29 $23.00 2,663 5,326 149 847 5,034 0.56 168,459 0.13 0.16 66 0.40 0.23 $17.77 472 860 24 147 852

$15.00 Indicated

Inferred

615,819 0.18 0.23 88 0.50 0.33 $25.56 2,396 4,631 119 676 4,420 1.02 115,696 0.14 0.18 70 0.43 0.26 $19.78 361 664 18 109 650

$20.00 Indicated

Inferred

403,021 0.21 0.27 89 0.50 0.38 $29.87 1,875 3,506 79 445 3,371 2.30 44,889 0.17 0.22 81 0.51 0.30 $23.62 166 312 8 51 301

Please See Table 1 for Notes to the Resource Table

Figure 2 below shows the resource pit shell and copper equivalent (“Cu Eq.”) modelled block grades for the Hushamu

deposit showing the Cu Eq. grade above the $11.50 cut-off.

Figure 2: Hushamu Resource Shell and Block Model Showing Grades

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

Details of Red Dog Resource Estimate

The Red Dog Resource Estimate includes a total of 50 diamond drill holes totalling 8,852 meters drilled by Northisle and

previous operators through the end of 2023, of which 9 holes totalling 2,175 meters were completed under the direction

of Northisle between 2011 and 2023.

Table 3 below summarizes the Red Dog Resource Estimate and shows the sensitivity of the estimate to cut-off

assumptions.

Table 3: 2024 Red Dog Mineral Resource Estimate

NSR

Cutoff Class

In Situ Tonnage and Grade Cu Metal

(mm lbs)

Au Metal

(000 Ozs)

Cu Eq.

Metal

(mm lbs)

Strip Tonnage Cu Au Cu Eq. NSR

($/T) (000 T) (%) (gpt) (%) ($/t) Ratio

$10.00 Indicated

Inferred

85,069 0.18 0.25 0.35 $32.63 339 684 655 0.37 10,204 0.14 0.18 0.25 $23.66 30 57 57

$11.50 Indicated

Inferred

83,129 0.18 0.25 0.35 $33.14 336 679 650 0.40 9,808 0.14 0.18 0.26 $24.18 30 56 56

$15.00 Indicated

Inferred

76,653 0.19 0.27 0.37 $34.81 326 657 629 0.54 7,954 0.15 0.20 0.29 $26.69 27 50 50

$20.00 Indicated

Inferred

63,762 0.21 0.29 0.41 $38.30 299 600 576 0.89 5,233 0.19 0.23 0.34 $31.57 21 38 39

Please See Table 1 for Notes to the Resource Table.

Figure 3 below shows the resource pit shell and modelled block grades for the Red Dog deposit showing the Cu Eq. grade

above the $11.50 cut-off.

Figure 3: Red Dog Resource Shell and Block Model Showing Grades

Details of Northwest Expo Resource Estimate

The Northwest Expo Resource Estimate includes a total of 30 diamond drill holes totalling 14,337 meters drilled by

Northisle and previous operators from 2005 through the end of 2023, of which 19 holes totalling 9,371 meters were

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

completed by Northisle between 2021 and 2023. The Northwest Expo estimate has not changed in methodology other

than to apply updated prices, recoveries, smelter terms and a $11.50/tonne cut-off to better reflect the potential for the

contemplated integrated development of the North Island Project.

Table 4 below summarizes the Northwest Expo Resource Estimate and shows the sensitivity of the estimate to cut-off

assumptions.

Table 4: 2024 Northwest Expo Mineral Resource Estimate

NSR

Cutoff Class

In Situ Tonnage and Grade Cu

Metal

(mm lbs)

Au

Metal

(000

Ozs)

Cu Eq.

Metal

(mm lbs)

Au Eq.

Metal

(000

Ozs)

Strip Tonnage Cu Au Cu Eq. Au Eq. NSR

($/T) (000 T) (%) (gpt) (%) (gpt) ($/t) Ratio

$10.00 Indicated

Inferred

45,463 0.11 0.64 0.65 0.77 $53.75 108 935 647 1,123 2.60 36,438 0.09 0.52 0.52 0.63 $44.10 70 612 414 738

$11.50 Indicated

Inferred

45,044 0.11 0.64 0.65 0.77 $54.15 108 933 646 1,120 2.65 35,611 0.09 0.53 0.53 0.64 $44.88 69 609 412 734

$15.00 Indicated

Inferred

43,771 0.11 0.66 0.67 0.79 $55.34 107 927 642 1,113 2.85 32,813 0.09 0.56 0.56 0.68 $47.57 68 596 404 717

$20.00 Indicated

Inferred

41,438 0.12 0.68 0.69 0.82 $57.47 105 911 632 1,094 3.20 28,727 0.10 0.62 0.61 0.74 $51.84 64 570 387 684

Please See Table 1 for Notes to the Resource Table.

Figure 4 below shows the resource shell and modelled gold equivalent (“Au Eq.”) block grades within the Northwest

Expo deposit above the $11.50 cut-off.

Figure 4: Northwest Expo Resource Shell and Block Model Showing Grades

Design Basis

The following Design Basis was established for the purpose of the Resource Estimate. The economic assumptions

presented here may change during the completion of the ongoing preliminary economic assessment for the North Island

Project. The Design Basis assumes the staged development of an integrated mining and processing facility. Blocks with

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

an estimated net smelter return of more than the Phase 2 cost, and less than the Phase 1 cost, are assumed to be

stockpiled for Phase 2 processing.

Table 5: Design Basis Key Assumptions

Assumption Units Quantity

Copper Price US$/lb $4.00

Gold Price US$/oz $1,910

Molybdenum Price US$/lb $21.00

Foreign Exchange C$/US$ 1.32

Concentrate Moisture % 9%

Cu Concentrate Treatment Charge US$/DMT $75.00

Cu Payable % 96.5%

Au Payable – NW Expo & Red Dog % 97.0%

Au Payable – Hushamu % 92.0%

Cu Refining Charge US$/lb $0.075

Gold Refining Charge US$/oz $5.00

Molybdenum Payable % 98.0%

Rhenium Payable % 50.0%

Molybdenum Refining Charge US$/lb $1.30

Concentrate Transport Charge $/WMT $85.00

NSR Royalty – NW Expo and Hushamu % 0%

NSR Royalty – Red Dog % 1%*

Phase 1 Processing and G&A Cost $/T $17.50

Phase 2 Processing and G&A Cost $/T $11.50

* Assumes repurchase of 2% of the outstanding 3% NSR for $2 million.

Table 6: Metallurgical Recoveries and Concentrate Grades

Northwest

Expo CMG

Northwest

Expo SCP

Red

Dog

Hushamu

CMG

Hushamu

SCP

Copper Process Recovery 73.0% 88.0% 89.7% 77.8% 75.4%

Gold Process Recovery* 91.0% 91.0% 85.0% 59.0% 54.0%

Cu Con Copper Grade 22% 25% 25% 22% 22%

Cu Con Gold Grade (g/t) 106 125 21 17 13

Mo Process Recovery 0% 0% 0% 49% 45%

Mo Con Mo Grade 0% 0% 0% 50% 50%

* Combined flotation and leach recovery

Summary of Metallurgical Testing Procedures and Results:

During 2023 and 2024, Northisle completed a metallurgical testing program on the Hushamu and Northwest Expo

deposits which informed the Design Basis and will further be incorporated into the in-progress preliminary economic

assessment for the North Island Project. No additional testing was completed on the Red Dog deposit as metallurgical

data obtained from test programs conducted prior to 2021 was referenced. The Company continues to optimize the

flowsheet and results may be refined further during the completion of future technical studies on the North Island

Project.

The recent test program was developed and managed by 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 qualified person confirms that the QA/QC measures applied by BaseMet conf orm to

industry standards for metallurgical testing laborat ories. These include appropriate checks and controls throughout the

sample preparation, bench scale testing and test product analysis components of the test program.

The Hushamu portion of the recent test program built on the metallurgical knowledge developed in previous test programs

and investigated coarser primary grind sizing as well as cyanide leaching of cleaner tails streams. The test program was

Northisle Copper and Gold Inc. | 14th Floor – 1040 West Georgia St. | Vancouver, BC | V6E 4H1

www.northisle.ca | [email protected]

conducted on master composites of SCP and CMG alteration material assembled from 9 drill holes in the 2021/2022 drill

campaign. The composites were assembled to more closely represent LOM feed grades, averaging 0.19% Cu and 0.27 g/t

Au.

The recent Hushamu results were analyzed along with test data from two earlier metallurgical programs (BaseMet BL0059

– 2016, ALS Metallurgy KM3409 – 2012) which tested composites with feed grades averaging 0.25 % Cu and 0.27 g/t Au.

Rougher results were averaged for tests with similar feed grades, chemical conditions and primary grind size to determine

expected rougher recoveries for CMG and SCP materials. Cleaner circuit recoveries were averaged from locked cycle tests

on each alteration, conducted within the same test programs, and achieved final concentrate grades averaging 21% Cu.

Hushamu cleaner tails generated from locked cycle tests in the recent test program were leached using 3000 ppm sodium

cyanide for 24 hours, achieving gold extractions of 48% and 44% for CMG and SCP materials, respectively. Sodium cyanide

leaching of the Hushamu rougher tails was not considered due to the relatively low gold content. The Hushamu

metallurgical results used for the design basis are presented in Table 7.

Table 7: Summary of Hushamu Metallurgical Results

Material

Grind Size µm P80 Feed Grades Flotation Distribution CN Leach

Ext. Net Au

Leach

Rec %

MRE Recoveries

Primary Regrind Cu (%) Au

(gpt) Stream Cu (%) Au (%) Au (%) Cu (%) Au (%)

CMG 150 15 0.22 0.22

Concentrate 77.8 44.5

77.8 59.2 Cleaner Tail 7.2 27.9 52.5 14.6

Rougher Tail 15.0 27.6

SCP 150 15 0.22 0.28

Concentrate 75.4 31.8

75.4 54.4 Cleaner Tail 15.1 49.7 45.4 22.6

Rougher Tail 9.5 18.5

Locked cycle flotation tests were conducted on master composites of CMG and SCP alteration material from the NW Expo

deposit. Bottle roll leach tests using sodium cyanide were conducted on both the rougher tails and cleaner tails from these

tests, to demo nstrate the potential for additional gold recovery. This test work was previously described in Northisle’s

press release titled “Northisle Announces Recoveries of 90% Gold and 80% Copper at Northwest Expo and accelerates 2024

Project Development Timeline” dated February 29, 2024.

Red Dog metallurgical performance is based on locked cycle flotation testing conducted by SGS in 2020. Bottle roll leach

tests conducted by BaseMet in 2016 on rougher and cleaner tails generated from similar feed samples and flotation

conditions were used as the basis for gold leaching extractions. The sample tested by BaseMet was a composite of ¼ HQ

drill core samples selected from 4 drill holes in the 2016 campaign. The current design considers processing both Red Dog

and Northwest Expo material with a flowsheet that utilizes froth flotation to generate a copper concentrate followed by

separate rougher and cleaner tails gold leach circuits.

It is proposed that bulk copper concentrate generated from Hushamu material would be processed through a Cu -Mo

separation circuit to recovery a molybdenum concentrate. No Cu -Mo separation circuit testing has been completed to

demonstrate the metallurgical performance of this process, however Mo recovery of 90% across the circuit has been

estimated as a reasonable industry standard for porphyry Cu -Mo deposits. Rhenium is expected to be associated with

molybdenite, therefore Re recovery to the final Mo concentrate is expected to match molybdenum recovery. An additional

90% factor is applied to the final Re recovery to reflect downstream processing losses. The molybdenum feed grades of

the Northwest Expo and Red Dog deposits are lower than Hushamu, so bulk copper concentrates from these deposits are

not considered for Cu-Mo separation processing at this time.

A summary of recoveries estimated for all three deposits is presented in Table 8.