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NORTHISLE 2025 PEA INDICATES 29% AFTER-TAX IRR AND $2 BILLION NPV FOR STAGED DEVELOPMENT OF THE NORTH ISLAND PROJECT NPV of $3.8 Billion with an After-tax IRR of 45% at spot prices

Economic Studies

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

www.northisle.ca | [email protected]

February 19, 2025 – All figures in C$ unless otherwise noted

TSX Venture Exchange Symbol: NCX

NORTHISLE 2025 PEA INDICATES 29% AFTER-TAX IRR AND $2 BILLION NPV FOR

STAGED DEVELOPMENT OF THE NORTH ISLAND PROJECT

NPV of $3.8 Billion with an After-tax IRR of 45% at spot prices

Highlights:

• The 2025 PEA outlines robust economics, unlocking copper value through gold

o Base Case: After-tax net present value (“NPV”) of $2 billion (US$1.5 billion) at a 7% discount rate, after-tax internal

rate of return (“IRR”) of 29%, 1.9-year payback period and 29-year life of mine (“LOM”)

o After-tax NPV of $3.8 billion (US$2.6 billion) at 7%, after-tax IRR of 45% and a 1.4-year payback at spot prices

o Phase 1 average annual production of 200,000 ozs Au and 48mm lbs Cu over 5 years, with 157 million lbs Cu Eq.

or approx. 307,000 ozs Au Eq. LOM

o LOM revenue of 48% copper, 45% Au, and 7% Mo at Base Case prices, and 50% Au, 44% Cu and 6% Mo at spot

o Phase 1 operating cash flow of $2 billion at Base Case prices supports rapid payback of 1.9 years and fully funds

Phase 2 expansion capex

• Among the lowest cost and capital intensity projects relative to peer group

o Two-phase approach at single plant site with Phase 1 at 40,000 tonnes per day (“tpd”), doubling to 80,000tpd

o NPV of $2.0 billion (US$1.5 billion) is 1.7 times initial capital investment of $1.1 billion (US$847 million) at Base

Case pricing and 3.3 times initial capex at spot prices

o Phase 1 cash cost of US$763/oz Au Eq. or US$1.49/lb Cu Eq. sits in first quartile globallyi

• Long-term opportunity spanning 35-kilometer porphyry district

o 29-year mine plan includes only 753Mt of material of the 905Mt Indicated and 214Mt Inferred Resource

o New discovery at West Goodspeed, located within 1km of Red Dog, not included in current resource

o $7 million fully funded exploration program focused on expanding higher margin and grade northwest corridor

• Furthers the Company’s sustainable development goals

o Reduced emissions from Phase 1 operations, increased electrification opportunities

o Estimated LOM carbon intensity among the lowest in Canada for open pit copper minesii

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

the positive results from a Preliminary Economic Assessment (the “202 5 PEA”) for its 100% owned North Island Project

(the “Project”) that demonstrate excellent economics from the staged development of the Project.

The 2025 PEA is based on a two-phase development of the Company’s 100% owned Northwest Expo and Red Dog deposits,

followed by the Hushamu deposit concurrent with a plant expansion. The 2025 PEA considers the processing of 753 million

tonnes of mineable material within three open pit deposits over a 29-year mine life. During the first phase, throughput is

approximately 40,000 tpd resulting in an initial capital expenditure of approximately $1.1 billion (US$849 million).

Production includes a combination of gold dor é and gold -rich copper concentrate . T he second phase contemplates

twinning the mill for a total of 80,000tpd in year 6 to produce copper concentrate (containing significant payable gold) ,

additional gold doré, and a molybdenum concentrate (containing payable rhenium). Phase 1 delivers a short payback

period of 1.9 years and strong operating cash flows (net of sustaining capital) of approximately $400 million per year that

provide a strong return and fully fund Phase 2 construction starting in year 5 (see Figure 4).

Dale Corman, Chairman, Cornerstone Shareholder, and Mining Hall of Fame recipient, commented: “I have always believed

that the North Island Project is among the most promising copper and gold projects in BC, and now, I believe it’s among

the most promising in the world. The results of the PEA highlight the Project’s economic potential and the opportunity

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

www.northisle.ca | [email protected]

across our 35km district. Our team continues to make disciplined discoveries which we expect will continue to add value

for shareholders.”

Sam Lee, President and CEO of Northisle added, “The 2025 PEA confirms our view that the North Island Project has the

potential to be among the best copper and gold projects in Canada. Our approach to optimizing the PEA was built upon

two strategic pillars: lowering the project capital intensity through a phased approach while maximizing overall project

value and returns. Upon achieving these goals, we now have a project that sharply distinguishes itself from other more

capital-intensive copper projects by unlocking our copper value through gold.

Of equal importance, we have just scratched the surface across our 35 -kilometer porphyry district. Through our fully

funded 2025 exploration program focused on the Northwest Corridor, we will test for the causative intrusion at Northwest

Expo, seek to expand the footprint of West Goodspeed both along strike and via fault offsets, and in-fill West Goodspeed

to enhance continuity. In our view, the combination of exploration potential and a robust development project at its core

make the North Island Project one of Canada’s most compelling copper AND gold projects.

With continued support of our First Nations partners, the BC and Federal Government, our shareholders and other

stakeholders, we look forward to our project providing meaningful benefits in the years and decades to come.”

Jagrup Brar, Minister of Mining and Critical Minerals stated “Responsible resource development of critical minerals in

partnership with First Nations is proven to expedite mining projects in B.C. That’s why we are pleased to see Northisle

continue to progress its North Island Project to unlock copper, one of Canada’s critical minerals. We look forward to

working with Northisle on obtaining efficient permitting decisions.”

The Company will host a conference call and webcast on February 19, 2025 at 11:00 AM Eastern time (8:00 AM Pacific

time). Details to access the call can be found below.

Key performance indicators are summarized in Table 1 below.

Table 1: 2025 Base Case Summary Project Metrics

Project

Stage

Production AISC

After-

tax

Avg.

Free

Cash

Flow

After-

tax

NPV

(7%)

After-

tax

IRR

GHG

Emissions

(kg CO2

/lb.)

Cu

(mm

lbs)

Au

(Koz)

Cu Eq.

(mm

lbs)

Au Eq.

(Koz)

Cu by-

product

(US$/lb)

Au by-

product

(US$/oz)

Cu Eq.

(US$/lb)

Au Eq.

(US$/oz) $ mm $ mm % Cu Cu

Eq.

Phase 1

(first 5

years)

average

48 200 151 294 $(3.23) $370 $1.83 $938 357

1,996 28.6 1.17 0.56 Life of

mine

(“LOM”)

average

75 137 157 307 $0.47 $93 $2.41 $1,232 199

Note: Cu Eq. based on Base Case metal prices and includes molybdenum and gold. See Table 2 for details.

2025 PEA Summary

The 2025 PEA was prepared in accordance with Nation al Instrument 43-101 Standards of Disclosure for Mineral Projects

(“NI43-101”) by Ausenco Engineering Canada ULC (“Ausenco”) in conjunction with an updated mine plan prepared by

Moose Mountain Technical Services (“Moose Mountain”) and incorporates the previously announced integrated resource

estimate for the North Island Project prepared by Moose Mountain (the “2024 Resource Estimate”). The 2025 PEA also

includes an updated Mine Waste Storage Facility (“MWSF”) design prepared by Ausenco and updated metallurgical test

work, also overseen by Ausenco. The Company plans to file the complete 2025 PEA report on SEDAR+ at www.sedarplus.ca

within 45 days of this press release.

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

www.northisle.ca | [email protected]

Table 2 summarizes the key findings of the 2025 PEA.

Table 2: 2025 PEA Economic Highlights

Base Case Economics Units Base Case

Net Present Value (after tax NPV 7%) $ millions 1,996

Net Present Value (after tax NPV 7%) US$ millions 1,477

Internal Rate of Return % 28.6

Payback Years 1.9

Phase 1 Initial Capital Cost $ millions 1,144 (US$847)

Phase 2 Expansion Capital $ millions 693 (US$513)

Sustaining Capital Cost $ millions 1,278 (US$946)

Economic Assumptions Units Base Case

Copper US$/lb 4.20

Gold US$/oz 2,150

Molybdenum US$/lb 21

Rhenium US$/kg 1,950

CAD:USD Exchange Rate US$/C$ 0.74

Base Case Annual Financial Metrics Units First 5 years LOM

Average Annual Revenue $ millions 855 902

Average Annual On-site Operating Costs $ millions 279 411

Avg. Ann. Operating Cash Flow (after tax) $ millions 418 290

Avg. Ann. Free Cash Flow (after tax) $ millions 357 199

The 202 5 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. There is no certainty that the projections described in the 2025 PEA will be realized. Mineral resources that are

not mineral reserves do not have demonstrated economic viability.

Table 3 provides a summary of the key operating metrics from the 2025 PEA.

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

www.northisle.ca | [email protected]

Table 3: 2025 PEA Operating Highlights

Operating Statistics Units Phase 1 (First 5

Years) Phase 2 Avg. LOM

Mine Life Years 5 23.7 28.7

Annual Throughput M tonnes 14.8 28.6 26.2

Waste to Processed Material Waste:Processed Material 1.43 0.74 0.81

Total Copper Recoveries % 86.7 79.3 80.1

Total Gold Recoveries % 83.1 57.4 62.3

Total Molybdenum Recoveries % NA 51.4 51.4

Average Annual Payable Production

Copper mm lbs 48 81 75

Gold Koz 200 123 137

Molybdenum Klbs NA 2,763 2,282

Cu Eq. mm lbs NA 158 157

Au Eq. Koz 294 309 307

C1 Cost – Cu Eq payable $/lb 1.49 2.15 2.04

C1 Cost – Au Eq payable $/oz 762 1,100 1,044

AISC – Cu Eq payable $/lb 1.83 2.52 2.41

AISC – Au Eq payable $/oz 938 1,291 1,232

CuEq = copper payable lbs + ((gold payable oz * gold price)/copper price) + ((molybdenum payable lbs *molybdenum price)/copper price)

AuEq = gold payable oz + ((copper payable lbs * copper price)/gold price) + ((molybdenum payable lbs *molybdenum price)/gold price)

Cash cost = operating costs + offsite costs – Rhenium credit

AISC = cash cost + royalties + sustaining capital + closure capital

Cu Eq. and Au Eq. calculated at Base Case metal prices

Economic Sensitivity

An economic analysis was conducted based on spot metal prices (the “Spot Price”) as of February 11, 2025 and assumed

no changes to any other modifying factors.

Table 4: 2025 PEA Economic Highlights

Spot Price Economics Units Spot Price1

Net Present Value (after tax NPV 7%) $ millions 3,754

Net Present Value (after tax NPV 7%) US$ millions 2,625

Internal Rate of Return % 45.1

Payback Years 1.4

Phase 1 Initial Capital Cost $ millions 1,144 (US$847)

Phase 2 Expansion Capital $ millions 693 (US$513)

Sustaining Capital Cost $ millions 1,278 (US$946)

Economic Assumptions Units Spot Price1

Copper US$/lb 4.67

Gold US$/oz 2,908

Molybdenum US$/lb 21

Rhenium US$/kg 2,417

CAD:USD Exchange Rate US$/C$ 0.70

1 – Spot price as of February 11th, 2025

Table 5 summarizes the after-tax sensitivities of NPV and IRR to metal prices.

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

www.northisle.ca | [email protected]

Table 5: 2025 PEA Post Tax Sensitivity Summary

Post-Tax Sensitivity to Metal Price (C$M)

Post-Tax NPV Sensitivity To Discount Rate ($M) Post-Tax IRR Sensitivity To Discount Rate

Commodity Price Spot

Price Commodity Price Spot

Price

Discount Rate $1,974 (20%) (10%) – 10% 20% –

Discount Rate $0 (20%) (10%) – 10% 20% –

3% 1,649 2,598 3,546 4,500 5,450 6,299 3.00% 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

5% 1,160 1,903 2,642 3,384 4,121 4,814 5.00% 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

7% 806 1,404 1,996 2,588 3,176 3,754 7.00% 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

8% 665 1,207 1,742 2,276 2,805 3,337 8.00% 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

10% 439 890 1,334 1,774 2,210 2,667 10.00% 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

Post-Tax NPV Sensitivity To OPEX ($M) Post-Tax IRR Sensitivity To OPEX

Commodity Price Spot

Price Commodity Price Spot

Price

OPEX

$1,974 (20%) (10%) – 10% 20% –

OPEX

$0 (20%) (10%) – 10% 20% –

(20%) 1,310 1,902 2,492 3,082 3,668 4,247 (20%) 21.2% 26.9% 32.2% 37.1% 41.8% 48.0%

(10%) 1,059 1,654 2,244 2,835 3,423 4,001 (10%) 19.0% 24.9% 30.4% 35.4% 40.2% 46.5%

– 806 1,404 1,996 2,588 3,176 3,754 – 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

10% 552 1,154 1,748 2,341 2,933 3,508 10% 14.0% 20.6% 26.6% 32.0% 37.0% 43.6%

20% 294 904 1,501 2,094 2,686 3,262 20% 11.0% 18.3% 24.6% 30.2% 35.3% 42.0%

Post-Tax NPV Sensitivity To Initial Capex ($M) Post-Tax IRR Sensitivity To Initial Capex

Commodity Price Spot

Price Commodity Price Spot

Price

Initial Capex

$1,974 (20%) (10%) – 10% 20% –

Initial Capex

$0 (20%) (10%) – 10% 20% –

(20%) 988 1,581 2,173 2,760 3,350 3,929 (20%) 21.9% 29.5% 36.3% 42.5% 48.2% 56.0%

(10%) 898 1,492 2,085 2,673 3,263 3,841 (10%) 18.9% 25.8% 32.0% 37.6% 42.9% 50.0%

– 806 1,404 1,996 2,588 3,176 3,754 – 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

10% 715 1,314 1,910 2,500 3,092 3,667 10% 14.7% 20.4% 25.7% 30.5% 35.1% 41.0%

20% 622 1,224 1,820 2,412 3,004 3,580 20% 13.2% 18.4% 23.4% 27.9% 32.1% 37.6%

Post-Tax NPV Sensitivity To Recovery Mill ($M) Post-Tax IRR Sensitivity To Recovery Mill

Commodity Price Spot

Price Commodity Price Spot

Price

Recovery Mill $1,974 (20%) (10%) – 10% 20% –

Recovery Mill $0 (20%) (10%) – 10% 20% –

(20%) 85 623 1,141 1,651 2,159 2,704 (20%) 8.1% 14.4% 19.9% 24.9% 29.6% 35.5%

(10%) 446 1,011 1,564 2,114 2,664 3,223 (10%) 12.5% 18.7% 24.3% 29.5% 34.2% 40.4%

– 806 1,404 1,996 2,588 3,176 3,754 – 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

10% 1,204 1,839 2,473 3,103 3,733 4,332 10% 20.6% 26.9% 32.6% 37.9% 43.0% 49.6%

20% 1,732 2,407 3,082 3,751 4,425 5,043 20% 24.8% 31.0% 36.7% 42.1% 47.2% 54.1%

Post-Tax NPV Sensitivity To Head Grade ($M) Post-Tax IRR Sensitivity To Head Grade

Commodity Price Spot

Price Commodity Price Spot

Price

Head Grade

$1,974 (20%) (10%) – 10% 20% –

Head Grade

$0 (20%) (10%) – 10% 20% –

(20%) (249) 298 778 1,248 1,712 2,152 (20%) 3.4% 10.8% 16.3% 21.3% 25.9% 31.5%

(10%) 312 858 1,390 1,918 2,445 2,952 (10%) 10.9% 17.2% 22.7% 27.8% 32.5% 38.5%

– 806 1,404 1,996 2,588 3,176 3,754 – 16.6% 22.9% 28.6% 33.7% 38.6% 45.1%

10% 1,288 1,946 2,603 3,255 3,908 4,559 10% 21.7% 28.1% 33.8% 39.3% 44.4% 51.3%

20% 1,766 2,488 3,205 3,923 4,642 5,365 20% 26.4% 32.9% 38.8% 44.4% 49.8% 57.2%

Note: FX sensitivity has only been applied to revenue in this study. Future studies will further model FX sensitivity. Spot

Price is US$4.67/lb Cu, US$2,908/oz Au, US$21/lb Mo, US$2,417/kg Re and an FX rate of 0.70.

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

www.northisle.ca | [email protected]

Figure 1: Sensitivity Summary Post-Tax NPV (7%)

Figure 2: Sensitivity Summary Post-Tax IRR

–

500.0

1,000.0

1,500.0

2,000.0

2,500.0

3,000.0

3,500.0

(25%) (20%) (15%) (10%) (5%) – 5% 10% 15% 20% 25%

NPV (C$M)

Commodity Price (+/-%) Total Opex (+/-%) Initial Capex (+/-%)

Recovery (+/-%) Head Grade (+/-%)

–

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

40.00%

45.00%

(25%) (20%) (15%) (10%) (5%) – 5% 10% 15% 20% 25%

IRR (%)

Commodity Price (+/-%) Operating Cost (+/-%) Initial Capex (+/-%)

Recovery(+/-%) Head Grade (+/-%)

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

www.northisle.ca | [email protected]

Figure 3: Annual Production Chart

Figure 4: Annual Cumulative FCF Chart

–

5,000

10,000

15,000

20,000

25,000

30,000

35,000

–

50

100

150

200

250

300

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Tonnes Milled (kt)

Metal Produced (Mlbs)

Year

Copper Equivalent Production Mill Feed

Phase 1 Phase 2

(4,000)

(3,000)

(2,000)

(1,000)

–

1,000

2,000

3,000

4,000

5,000

6,000

(800)

(600)

(400)

(200)

–

200

400

600

800

1,000

1,200

-2 -1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Cumulative FCF ($ Millions)

$ Millions

Year

Post-Tax CF - Phase 1 Post-Tax CF - Phase 2

Initial Capex Expansion Capex

Post-Tax Cumulative FCF

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

www.northisle.ca | [email protected]

Comparison to 2021 PEA

Table 6: Comparison of 2021 PEA to 2025 PEA

Information/Data Type 2021 PEA 2025 PEA

Economics $1.1 billion After-tax NPV (8%) and 19% After-tax IRR $2.0 billion After-tax NPV (7%) and 29% After-tax IRR

Initial Capital Expenditure $1.4 billion $1.1 billion (US$847 million)

Payback of initial capital

expenditure 3.9 years 1.9 years, expansion capital expenditure paid out of after-

tax free cash flow

After-Tax Free Cash Flow Average annual after-tax free cash flow of $321 million

during the first 6 years, $224 million LOM

Average annual after-tax free cash flow (includes all capex)

of $357m first 5 years, $199m LOM

AISC US$2.01/lb Cu Eq over first 6 years, US$2.14/lb Cu Eq

LOM US$1.83/lb Cu Eq over first 5 years, US$2.41/lb Cu Eq LOM

Annual Production

First 6-year average payable production of 112mm lbs

Cu and 112 koz Au; LOM average payable production

of 96mm lbs Cu and 100koz Au, including 1.0kt Mo

First 5-year average payable production of 200koz Au and

48mm lbs Cu; LOM average annual payable production of

75mm lbs Cu and 137 koz Au, plus 1.0kt Mo and Re credits

Mine Life 22 years 29 years

Mine Capacity 75 ktpd for Red Dog and Hushamu mine and mill

2 Stage production plan, 40 ktpd expanding to 80 ktpd to

provide early processing of Au rich NW Expo material to

significantly improve project economics

Processing and Metallurgy Flotation of Red Dog and Hushamu material to

produce Cu concentrate and Molybdenum concentrate

Flotation plus cyanide leach of rougher and cleaner (Ph 1)

and cleaner (Ph 2) flotation tails to add 15-25%

improvement in Au recovery by producing Au doré

Project Capital Expenditure Single Phase initial capital - more difficult to finance

2 Phase production provides significantly reduced initial

capital to facilitate project financing. Second phase

expansion paid entirely out of free cash flow.

Information/Data Type 2021 PEA 2025 PEA

Pricing Base Case Spot Price Base Discount

to Spot Base Case Spot Price Base Discount

to Spot

Cu Price US$/lb 3.25 3.51 7% 4.20 4.67 10%

Au Price US$/oz 1,650 1,835 10% 2,150 2,908 26%

Mo Price US$/lb 10 10 0% 21 21 0%

Re Price US$/kg 1,256 1,256 0% 1,950 2,417 19%

Exchange Rate USD/CAD 0.75 0.75 0% 0.74 0.70 (6%)

Production LOM First 5 years LOM

Mine Life Years 22 5 28.7

Total Mill Feed kt 600,359 74,133 752,164

Strip Ratio Waste : Processed 0.71 1.43 0.81

Mill Design Capacity tpd 75,000 40,000 80,000

Processing and Metallurgy Cu and Au flotation to produce Cu con

and separate Moly con

Cu and Au flotation to produce Cu con and

separate Moly con, cyanide leach of NW Expo and

Red Dog ore rougher and cleaner tails, and

Hushamu cleaner tails

Total Copper Recovery % 86% 86.7 80.1

Total Gold Recovery % 47% 83.1 62.3

Total Molybdenum Recovery % 60% 51.4 51.4

Average Annual Cu Production mm lbs 96 48 75

Average Annual Au Production koz 100 200 137

Average Annual Mo Production kt 1.1 N/A 1.0

Annual CuEq Production mm lbs 156 151 157

Total Cu Recovered mm lbs 2,035 240 2,168

Total Au Recovered koz 2,143 1,002 3,932

Total Mo Recovered kt 25 N/A 30

Total CuEq Recovered mm lbs 3,430 753 4,509

Operating Cost

Mining Cost $/t mined 2.32 3.16 3.12

Processing Cost $/t milled 5.58 10.39 9.36

G&A Cost $/t milled 0.38 1.25 0.68