G2 Goldfields Delivers Maiden PEA for the High-Grade Oko Gold Project

2025-12-18

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(All amounts are in US$)

PEA Highlights:

High-grade updated resource: Underpinned by G2’s updated Mineral Resource Estimate, including 1.6 Moz Au at 3.24 g/t Au (Indicated) and 1.9 Moz Au at 3.31 g/t Au (Inferred), incorporating six months of new drilling. Long life, significant production and industry-leading margins: 14-year LOM underground and open pit operation with average annual gold production of 281,000 ounces at AISC¹ of $1,137/oz Au from years 2 through 11. Attractive capital profile: Initial capital expenditures of $664 million (including 20% contingency) and sustaining capital expenditures¹ of $366 million over the LOM. Robust economics and fast payback: After-tax NPV5% of $2.6 billion, IRR of 39% and payback of 2.6 years at $3,000/oz Au (Base Case); After-tax NPV5% of $4.2 billion, IRR of 54% and payback of 2.0 years at $4,000/oz Au.

TORONTO, Dec. 18, 2025 (GLOBE NEWSWIRE) -- G2 Goldfields Inc. (“G2” or the “Company”) (TSX: GTWO; OTCQX: GUYGF) is pleased to announce the key findings from the Company’s Preliminary Economic Assessment ("PEA") for the high-grade Oko Gold Project (“Oko” or the “Project”) in Guyana, South America.

Daniel Noone, CEO of G2, stated, “This PEA places the Oko Project firmly within one of the most attractive development projects globally. The PEA demonstrates the Project has the potential to generate very significant annual production at an average AISC cost of US$1,137/oz and is hosted in mining-friendly Guyana which actively promotes the development of large-scale gold mining. Moreover, the Project tenements host significant exploration potential, with multiple drill programs active across various adjacent and near-mine targets. We will be aggressively moving the Oko Project to feasibility and construction as we continue to explore this emerging gold mining district.”

Overview

The PEA outlines a combined open pit (“OP”) and underground (“UG”) operation with a 14-year life of mine (“LOM”), based on drilling completed up to August 31, 2025, incorporating 1.6 million ounces of gold in the Indicated category and 1.9 million ounces of gold in the Inferred category, with production averaging 281,000 ounces per year from years 2 through 11. Total production over the entire 14-year mine life is estimated at 3.2 million ounces gold with an industry leading all-in sustaining cost¹ (“AISC”) of $1,191 per ounce ($1,137 per ounce from years 2-11). Oko is envisaged as a mix of conventional OP mining and mechanized long hole open stoping UG mining, with on-site treatment of the mined material processed through a conventional circuit consisting of comminution, gravity concentration, cyanide leach and adsorption via carbon- in-leach (“CIL”), carbon elution and gold recovery circuits. The OP mine is anticipated to have a LOM of six years, including 2 years of pre-stripping, while the UG mine is anticipated to have a LOM of 14 years, including 18 months of development. The PEA is based upon the Company’s updated Mineral Resource Estimate (“MRE”) with an effective date of November 20, 2025. A technical report (the "Technical Report") prepared in accordance with National Instrument 43-101 (“NI 43-101”) will be filed on the Company’s website and under its SEDAR+ profile within 45 days of this news release.

Click here to view a 3D model of the Oko Gold Project, Guyana

Table 1: Oko Preliminary Economic Assessment Highlights

Notes to Table 1: Total cash costs include mining, processing, surface infrastructures, transport, G&A and royalty costs. AISC includes total cash costs, sustaining capital expenditures to support the on-going operations, and closure/reclamation. Non-GAAP financial performance measures with no standardized definition under IFRS®. Refer to “_Non-GAAP Financial Measures_” at the end of this press release. 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. There is no certainty that the PEA will be realized.

Table 2: LOM Sensitivity Analysis

| Key Financial Metrics | Units | Gold Price per Ounce (US$) | | | | | | | | | | | $2,000 | | $2,500 | $3,000 (Base Case) | | $3,500 | | $4,000 | | | | Average Operating Cash Cost ¹(LOM) | US$/oz | | 1,026 | | 1,046 | 1,067 | | 1,088 | | 1,108 | | Average AISC¹ (LOM) | US$/oz | | 1,150 | | 1,170 | 1,191 | | 1,211 | | 1,232 | | Pre-Tax NPV5% | US$M | | 1,257 | | 2,364 | 3,471 | | 4,578 | | 5,685 | | Pre-Tax IRR | % | | 24 | | 36 | 46 | | 55 | | 63 | | After-Tax NPV5% | US$M | | 897 | | 1,730 | 2,561 | | 3,392 | | 4,223 | | After-Tax IRR | % | | 20 | | 31 | 39 | | 47 | | 54 | | Payback | Years | | 4.4 | | 3.2 | 2.6 | | 2.3 | | 2.1 | | Average Annual EBITDA¹ (LOM) | US$M | | 222 | | 331 | 441 | | 550 | | 659 | | Peak Annual EBITDA¹ (Year 6) | US$M | | 337 | | 481 | 634 | | 788 | | 942 | | Free Cash Flow¹ (LOM) | US$M | | 1,520 | | 2,670 | 3,819 | | 4,968 | | 6,117 |

Notes to Table 2: Total cash costs include mining, processing, surface infrastructures, transport, G&A and royalty costs. AISC includes total cash costs, sustaining capital expenses to support the on-going operations, and closure/reclamation. EBITDA reflects net income excluding interest, taxes, depreciation and amortization expenses. Free cash flow reflects cash from operations, [less initial and sustaining capital expenditures and reclamation costs]. Non-GAAP financial performance measures with no standardized definition under IFRS®. Refer to the note at the end of this press release.

Location, Access and Infrastructure

Oko is located in the Cuyuni-Mazaruni Region (Region 7) of north-central Guyana. The Project lies approximately 120 km west-southwest of Georgetown, the capital city, and 60 km west of the town of Bartica, the capital city of Region 7 and is easily reached by an existing road network.

Mining and processing infrastructure will be located at the Project’s site. The Project will require construction of the following infrastructure: 10,000 tonnes per day (“tpd”) process plant, offices, truck shop and warehouse, new camp accommodation, surface water management facility, service and haulage roads and an initial tailings management facility. An existing airstrip will be upgraded and used for emergencies and time sensitive transport.

Figure 1 – Oko District Plan View

Mineral Resource Estimate

The PEA is based on the updated MRE presented in Table 3 below, totalling 1.6 million ounces gold (Indicated) and 1.9 million ounces gold (Inferred) from five deposits: Oko Main Zone (“OMZ”), Ghanie, Northwest Oko (“Oko NW”), North Oko (“Oko N”) and the New Oko Discovery. The bulk of the gold mineralization lies along a prominent 2.5 km long north-south structure comprised of the high-grade OMZ deposit and a bulk mineable, disseminated mineral resource at Ghanie. Importantly, OMZ includes high-grade UG Indicated mineral resources of 741,600 ounces at 13.63 grams per tonne gold (“g/t Au”) and 522,100 ounces at 6.77 g/t Au. The New Oko Discovery lies approximately 8.5 km to the north of these deposits and was only discovered in March 2025.

The MRE includes all drilling data obtained up to the end of August 2025 with a total inventory of 666 drill holes across 170,329 metres. The estimate was prepared by Micon International Limited (“Micon”) in accordance with NI 43-101 with an effective date of November 20, 2025.

Table 3 – Oko Project Mineral Resource Estimate Summary

| Deposit | Mining Method | Category | Tonnage (t) | Gold Avg. Grade (g/t) | Contained Gold (oz) | | Oko Main Zone (OMZ) | OP | Total Indicated | 1,132,000 | 2.01 | 73,000 | | Total Inferred | 509,000 | 0.75 | 12,300 | | | | UG | Total Indicated | 1,693,000 | 13.63 | 741,600 | | | Total Inferred | 2,398,000 | 6.77 | 522,100 | | | | OP + UG | Total Indicated | 2,825,000 | 8.97 | 814,600 | | | Total Inferred | 2,907,000 | 5.72 | 534,400 | | | | | | | | | | | Ghanie | OP | Total Indicated | 6,574,000 | 1.85 | 390,300 | | Total Inferred | 4,128,000 | 1.01 | 133,800 | | | | UG | Total Indicated | 1,064,000 | 6.45 | 220,800 | | | Total Inferred | 7,409,000 | 4.72 | 1,123,300 | | | | OP + UG | Total Indicated | 7,638,000 | 2.49 | 611,100 | | | Total Inferred | 11,537,000 | 3.39 | 1,257,100 | | | | | | | | | | | New Oko Discovery | OP | Total Indicated | 5,090,000 | 1.18 | 193,800 | | Total Inferred | 1,269,400 | 0.88 | 36,100 | | | | UG | Total Indicated | 18,000 | 1.90 | 1,100 | | | Total Inferred | 590,000 | 2.05 | 38,900 | | | | OP + UG | Total Indicated | 5,108,000 | 1.19 | 194,900 | | | Total Inferred | 1,859,000 | 1.25 | 75,000 | | | | | | | | | | | Oko N | OP | Total Inferred | 1,293,000 | 0.78 | 32,500 | | | | | | | | | Oko NW | OP | Total Inferred | 374,000 | 0.94 | 11,300 | | | | | | | | | Entire Oko Project | OP + UG | Total Indicated | 15,571,000 | 3.24 | 1,620,600 | | Total Inferred | 17,970,000 | 3.31 | 1,910,300 | | | | | | | | | |

Notes to Table 3:

1. The effective date of this MRE is November 20, 2025. 2. The MRE presented above uses economic assumptions for both surface mining in saprolite and fresh rock, and underground mining in fresh rock only. 3. The MRE has been classified in the Indicated and Inferred categories following spatial continuity analysis and geological confidence. There are no Measured resources at the Oko Project this time. 4. Density varied regolith and weathering with ranges from 1.420 g/cm3 to 1.629 g/cm3 in the saprolite, 1.880 g/cm3 to 2.320 g/cm3 in the saprock and 2.650 g/cm3 to 2.763 g/cm3 in the fresh rock. 5. The calculated gold cut-off grades to report the MRE for surface mining vary from 0.23 g/t Au to 0.48 g/t Au in saprolite, and 0.28 g/t Au to 0.30 g/t Au in fresh rock. For underground mining the reporting cut-off grades vary in fresh rock from 1.21 g/t Au to 1.30 g/t Au. 6. The following economic parameters were used for generating cut-off grades:

• A gold price of US$2,500/oz. • Metallurgical recoveries for the New Oko Discovery deposit are 93% in saprolite and 95% in fresh rock, for the North Oko and Oko Main deposits are 98% in saprolite and 98% in fresh rock, for the Ghanie are 96% in saprolite and 91% in fresh rock, and for Northwest Oko deposit are 48% in saprolite and 48% in fresh rock. • Densities • Mining open pit costs of US$2.5/t in saprolite and US$2.75/t in fresh rock were used with underground mining costs of US$75.0/t. • Processing costs of US$12/t for saprolite and US$15/t for fresh rock. • A General and Administration cost of US$2.5/t. • For the New Oko Discovery deposit a transportation cost of $8/oz of gold was added. • Royalties of 8% for surface mining and 3% for underground mining were applied to all deposits.

7. For surface mining the open pits used slope angles of 27° in saprolite and 47° in fresh rock. 8. The QP has considered that the transition between the OP mining and UG mining scenarios will result in the need for crown pillars. However, at this time, the crown pillars are considered to be recoverable, therefore the QP has considered them as part of the MRE. 9. The Oko Main deposit has had subcontracted mid-scale miners engaged in underground mining operations on the licence in the past. G2 has provided the QP with digitized vertical maps of the voids, as of 2022, and the current mineral resources have been discounted based upon this information. However, there are no updated surveys, maps or production records for the underground mining operations from 2022 to present. G2 is of the belief that there are no subcontracted miners currently present on the Oko, Ghanie and New Oko Discovery claims. 10. The Oko Main and Ghanie block models are orthogonal and use a parent block size of 10 m along strike, 3 m across strike, and 5 m in height, with minimum child block of 2 m x 0.5 m x 1 m. The Northwest Oko block model is rotated to 307 degrees, and uses a parent block size of 10 m along strike, 3 m across strike, and 10 m in height, with a minimum child block of 2 m x 1 m x 2 m. The Oko North block model is rotated 31 degrees, and uses a parent block size of 12 m along strike, 6 m across strike, and 6 m in height, with a minimum child block of 6 m x 1.5 m x 3 m. The New Oko Discovery block model is rotated 60 degrees, and uses a parent block size of 12 m along strike, 3 m across strike, and 3 m in height, with a minimum child block of 6 m x 1.5 m x 1.5 m. 11. The open pit optimization uses a re-blocked size of:

• 9 m long by 10 m wide by 10 m high for the Oko Main and Ghanie deposits. • 9 m long by 12 m wide by 9 m high for the New Oko Discovery deposit. • 12 m long by 12 m wide by 12 m high for the North Oko deposit. • 9 m long by 10 m wide by 10 m high for the Northwest Oko deposit.

12. The underground optimization uses mining shapes of 20 m long by 30 m high for the Oko Main, Ghanie, and New Oko Discovery deposits, with a minimum mining width of 1.5 m. 13. The mineral resources described above have been prepared in accordance with the current Canadian Institute of Mining, Metallurgy and Petroleum Standards and Practices. 14. Mr. William J. Lewis, P.Geo. from Micon International Limited is the Qualified Person (QP) for this MRE. 15. Numbers have been rounded to the nearest thousand tonnes and nearest hundred ounces. Differences may occur in totals due to rounding. 16. Mineral Resources are not Mineral Reserves as they have not demonstrated economic viability. The quantity and grade of reported Inferred Mineral Resources are uncertain in nature and there has been insufficient exploration however, it is reasonably expected that a significant portion of Inferred Mineral Resources could be upgraded into Indicated Mineral Resources with further exploration. 17. The QP has not identified any current legal, political, environmental, or other factors that could materially affect the potential development of the MRE.

Figure 2 – Oko Project Plan View of All Deposits

Figure 3 – OMZ & Ghanie Deposits Long Section Looking East: HG Blocks with OP and UG Mining Constraints

Figure 4 – OMZ & Ghanie Deposits Vertical Section Looking North: HG Blocks with OP and UG Mining Constraints

Mining and Production

Mining at the Project is planned to integrate both conventional open pit mining methods and mechanized long hole open stoping underground mining. The OP mine will have a LOM of six years, including 2 years of pre-stripping, while the UG mine will have a LOM of 14 years, including 18 months of development.

The open pit mine is expected to have a production rate that averages 4,500 tpd over a 14-year LOM. A total of 124.1 Mt of waste rock is planned to be mined, with 5.4 Mt of mineralization in saprolite and 17.4 Mt of mineralization in fresh rock, for a total strip ratio of 5.4:1, at an average grade of 1.03 g/t Au containing 0.75 Moz Au. OP mine designs and production scheduling were developed using optimized pit shells generated at a gold price of US$2,500/oz, with pit shell selection informed by appropriate revenue factor analysis to balance near-term economics and LOM value. The resulting open pit mine plan supports conventional drill-and-blast mining using an owner-operated fleet, with material movement planned to utilize 13 haul trucks and 2 hydraulic excavators.

The UG operation will take place in three areas: OMZ, Ghanie and the New Oko Discovery and will employ a long hole open stoping mining method via ramps, including transverse stoping and longitudinal stoping variations. The average UG production rate is expected to be 1,900 tpd of mineralized material, comprising approximately 1,600 tpd from stope production and 300 tpd from lateral development, from each zone. A total of 21.3 Mt of mineralized material is expected to be mined at an average diluted gold grade of 3.9 g/t Au. UG mine designs were based on the following parameters: a gold price of US$2,500/oz, a minimum mining width of 1.5 meters, and area-specific cut-off grades ranging from 1.215 g/t Au (Oko) to 1.31 g/t Au (Ghanie). The plan incorporates an effective minimum mining width of 3.0 meters (post-dilution) and accounts for mining recovery factors of 95% for longitudinal stoping.

Figure 5 - Production Profile

Notes to Figure 5:

1. LOM averages for years 2-11; AISC¹ based on a LOM gold price of US$3,000/oz Au

Processing and Recovery

The proposed process plant design for Oko is based on a standard metallurgical flowsheet to treat gold bearing material and produce doré. The process plant is designed to nominally treat 3.6 Mt per year and will consist of comminution, gravity concentration, cyanide leach and adsorption via CIL, carbon elution and gold recovery circuits. CIL tailings will be treated in a cyanide destruction circuit and pumped to a tailings storage facility. During the open pit operational period, the ramp-up period is 6 months.

Table 4: Metallurgical Recoveries

| Feed | Grade (g/t) | Recovery (%) | Mill Feed (%) | | Saprolite | 0.87 | 93.3 | 12.0 | | Fresh Rock | 2.60 | 94.1 | 88.0 | | Total (LOM) | 2.39 | 94.0 | 100.0 |

Operating Costs

LOM total site costs are estimated at approximately $947 per ounce of gold produced, excluding royalty costs, as summarized below. The PEA incorporates two federal royalties: a 3.0% net smelter return (“NSR”) royalty for underground production and an 8.0% NSR royalty for open pit production. Precedence for these royalty rates is achieved from multiple large scale existing mining agreements in Guyana. The LOM AISC¹ is estimated to be $1,191 per ounce of gold produced based on average annual gold production of 228,000 ounces over the 14-year LOM. Average annual production from years 2 through 11 is 281,000 ounces at an AISC¹ of $1,137 per ounce.

Table 5: LOM Operating Costs Summary

| Costs | Unit Cost (USD/t milled) | Unit Cost (USD/oz) | | Mining Costs - OP | 9.26 | 128.14 | | Mining Costs - UG | 34.21 | 473.23 | | Processing Costs | 16.75 | 231.78 | | G&A Costs | 7.53 | 104.22 | | Transport & Refining | 0.66 | 9.17 | | Total Site Cost | 68.42 | 946.54 | | Royalty Costs | 8.71 | 120.49 | | Total Operating Cash Costs¹ | 77.13 | 1067.03² | | Sustaining Capex³ | 8.29 | 114.70 | | Closure Costs | 0.65 | 9.04 | | AISC1 | 86.07 | 1190.77² |

Note to Table 5: “AISC” and “Total Operating Cash Costs” are non-GAAP financial performance measures with no standardized definition under IFRS®. Refer to “_Non-GAAP Financial Measures_” at the end of this press release.

Capital Costs

Initial capital costs are estimated at $664 million, including contingencies of $108 million (20%) with LOM sustaining costs estimated at $366 million. These estimates are based on current costs and quotes received from potential local vendors and references and experience from similar operations.

The main components of the $664 million initial capital costs (including contingencies) include: $278 million for the processing plant equipment and buildings plus $56 million indirect costs to construct the process plant, $96 million for mining equipment and surface preparation, $72 million for surface civil and infrastructure, $46 million for capitalized pre-stripping, and $116 million for owner’s costs. The main components of the $366 million sustaining capital expenditures include: $182 million for mining equipment, $74 million for tailings and water treatment, $62 million for process plant equipment, and $48 million contingency.