Omai Gold Drills 708m Averaging 1.06 g/t Au from 365m at Gilt Creek Deposit Including Multiple Higher Grade Intervals

Toronto, December 18, 2025 - Omai Gold Mines Corp. (TSXV: OMG) (OTCQB: OMGGF) ("Omai Gold" or the "Company") is pleased to announce assay results from the Company's second hole drilled on the Gilt Creek gold deposit. The Gilt Creek deposit is one of two orogenic gold deposits at its 100%-owned Omai Gold Project in Guyana. Hole 25ODD-122(w) drilled 708m of the Omai Stock, an intrusive rock unit that produced 2.4 million ounces of gold between 1993-2005² from the upper portion from surface to a vertical depth of approximately 250m. Hole 25ODD-122(w) was drilled from surface to a total depth of 2,014m with results previously report for the lower part of the hole that confirmed the presence of the adjacent Wenot deposit at a depth of approximately 1,200m, or 700m below the known Wenot gold mineralization. Hole 122w showed that the Wenot shear at this depth hosted seven significant gold zones (news release November 12, 2025). The upper part of hole 122(w) was drilled from surface through a mafic volcanic sequence, then through the known diabase dike, and first intersected significant gold mineralization at a vertical depth of approximately 260m. Gold mineralization proved extensive throughout the Gilt Creek intrusion and extends into the surrounding volcanic rocks as well. A 708.1m interval in Hole 122(w) averaged 1.06 g/t Au with multiple intervals with higher grades, as shown in figure 1, Table 1 and as highlighted below:

Highlighted higher grade zones from the upper part of hole 25ODD-122w include:

• 1.06 g/t Au over 708.1m (from 364.9) includes
  • 1.78 g/t Au over 46.2m (from 635.6 downhole) includes
    • 4.88 g/t Au over 7.0m (from 566.3m)
  • 1.32 g/t Au over 99.2m (from 702.0m) includes
    • 5.7 g/t Au over 8.0m (from 766.9m)
  • 3.10 g/t Au over 24.0m (from 395.5m)
  • 1.99 g/t Au over 32.0m (from 462.0m)
  • 2.98 g/t Au over 17.8m (from 643.8m)
  • 2.04 g/t Au over 43.2m (from 952.2m)

Elaine Ellingham, President & CEO, commented: "The much awaited results from Hole 122 further confirm the extent of gold mineralization within and beyond the known deposit. These assay results from the upper part of the 2,014m long hole show the robust and continuous nature of the gold-mineralized regime within the Gilt Creek quartz-diorite intrusive stock. This new hole, together with our earlier hole 095, provide valuable structural data for rock mechanics and material for metallurgical sampling, both that allow us to advance our mine plan for our upcoming updated Preliminary Economic Assessment ("PEA") that will include the Gilt Creek deposit. Due to the extent of mineralization and abundance of visible (coarse) gold, all samples >0.5 g/t Au were also assayed using a metallic screening process that provides a more representative total grade than fire-assay on a 50g sample alone. The downside was the additional turnaround time.

Mineralization in the Gilt Creek deposit first occurs just 46m downhole with 1.37 g/t Au over 7.5m in saprolite and ends at 2,014m with 3.61 g/t Au over 4.4m within less than 5m of the end of the hole in the adjacent Wenot deposit. This long hole across the two deposits exemplifies the sheer extent of gold mineralization on the Omai property."

The Gilt Creek orogenic gold deposit is located less than 500m north of the Wenot deposit, which has been the focus of most of the Company's drilling and resource expansion, as Wenot is predominantly an open pit target. The Gilt Creek gold deposit is hosted mostly within the Omai quartz diorite stock, but gold zones also occur within the adjacent volcanic rocks.

Hole 25ODD-122(w) was collared on the northwest flank of the old Gilt Creek pit. This is also at the eastern end of the recently drilled near-surface BBH gold trend. In fact, the initial gold zone in hole 122 of 1.71 g/t Au over 6.0m occurs in saprolite within 40m of surface and is part of the BBH target area. Hole 122 then drilled through mafic volcanic rocks to a downhole depth of 299m where it intersected the well-known diabase dike, with a true thickness of approximately 138m. Hole 122 was wedged within the diabase dike in order to flatten it sufficiently to reach the ultimate projected target depth under Wenot for this hole. It continued as hole 122w.

Below the diabase dike but before drilling into the intrusive complex, both hole 095 and 122 drilled a small interval of the surrounding mafic volcanics. In hole 122w, a gold zone within the volcanics assayed 3.10 g/t Au over 24.0m. Similarly in hole 095 the volcanics hosted gold mineralization, with assays of 2.09 g/t Au over 10.5m and a second zone of 1.59 g/t Au over 7.5m.

The Gilt Creek intrusive complex was first intersected at 367.5m downhole, continuing to 1078.5m, a total of 711m, with gold mineralization throughout much of this (Figure 1). All 711m of the Gilt Creek Intrusive drill core was sampled and 226 of the 572 samples or 40% assayed greater than 0.5 g/t Au (Figure 2). Interestingly, Iamgold drilled approximately 27,000m in 46 holes in 2006-7 in this lower part of the Gilt Creek deposit and similarly had 41% of the samples assaying greater than 0.5 g/t Au. Hole 24ODD-095 also had 39% of Gilt Creek samples assaying over 0.5 g/t Au. Detailed assay results for hole 122 and 122w are provided in Table 1.

The Gilt Creek drill holes (24ODD-095 and 25ODD-122) achieve several objectives; they: 1) assist in mine planning and metallurgical studies that will facilitate inclusion of Gilt Creek into an updated Preliminary Economic Assessment ("PEA") mine plan expected in H1 2026, 2) test and verify historical drilling and at the same time explore the lateral extent of gold mineralization beyond that previously identified, and 3) assist in the geological modelling of the Gilt Creek deposit in order to assess the overall exploration potential and extent of this very large gold system on the broader Omai property.

To facilitate mine planning, a televiewer system surveyed hole 095 in early 2025, together with select holes at the Wenot deposit. This optical and acoustic system provides detailed in-situ mapping of all rock structures, giving quality data to guide mine design and assist in a greater understanding of the structural geology. Neither hole 122(w) nor hole 095 encountered any high pressure or noteworthy water return during drilling or televiewer surveying.

Hole 122 was designed to continue much further, to test the adjacent Wenot gold deposit that lies only 450m south of the Gilt Creek deposit. The hole reached an impressive downhole depth of 2,014m and was successful in encountering the Wenot shear corridor at 1,739m downhole. It continued through 275m of the shear corridor, still within the Wenot shear zone at the end of the hole and with significant mineralization of 3.61 g/t Au over 4.4m, including VG within 5m of the end of the hole. Seven significant gold zones were encountered in this depth extension of Wenot, at the bottom of this same hole 122(w).

As noted upon the completion of hole 095, the sheer extent of gold mineralization within the Gilt Creek intrusive is impressive, well illustrated by the histogram in figure 2. By applying the same cut-off grade of 1.5 g/t Au as was used in the resource estimate³ (established for a US$1,700/oz gold price), a cumulative 150.4m (not continuous) has a weighted average grade of 3.20 g/t Au, very similar to the resource grade. In hole 095, it was noted that 198.3m (not continuous) has a weighted-average grade of 2.78 g/t Au, both comparable with the resource grade.

Gilt Creek Deposit Background

The Gilt Creek gold deposit is a large 500m by 275m compact, intrusion-hosted orogenic gold deposit. It is located approximately 500m north of the Wenot gold deposit on the Omai property (Figure 1). The Mineral Resource Estimate³ ("MRE") for Gilt Creek comprises Indicated Resources of 1,151,000 ounces gold averaging 3.22 g/t Au in 11.1 million tonnes ("Mt") and Inferred Resources of 665,000 ounces gold averaging 3.35 g/t Au in 6.2 Mt, using a 1.5 g/t Au cutoff and a US$1,700/oz gold price. Initial conceptual engineering studies anticipate a ramp from surface to access this deposit for underground mining. The very wide mineralized zones are likely amenable to sub-level open stoping and transverse open stoping, with follow-up cut-and-fill mining.

The upper portion of this Gilt Creek gold deposit was open pit mined between 1993 and 2005², producing 2.4 million ounces averaging 1.5 g/t Au. Continuation of this deposit at depth was confirmed by IAMGold Corp. in 2006-2007 with 46 drill holes totalling approximately 27,000m. This drilling showed gold mineralization down to a depth of 967m below surface, although only sparse drilling was completed to that depth.

Significantly, approximately 80% of the Gilt Creek gold Mineral Resource Estimate¹ is relatively shallow, lying at vertical depths of between 280m and 600m. Limited drilling of the Omai intrusion below 600m continues to encounter gold mineralization, but with drilling too sparce to include in a Resource. It provides evidence that gold mineralization within the Omai intrusion continues to greater depths, and Hole 122 drilled gold mineralization within the intrusion down to a vertical depth of 850m but laterally beyond the previously indicated limits.

Figure 1. Omai Gold property geology map showing Gilt Creek and Wenot deposits and Location of Diamond Drill Hole 25ODD-122

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Figure 2. Cross section Illustrating Location of Hole 122w Relative to Gilt Creek and Weno Deposits, Omai Gold Project, Guyana

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Photo 1. Visible Gold in Quartz Vein within Gilt Creek Gold Deposit (Hole 122W @ 652.7m- left and 656.1m - right and 1333.1m - bottom)

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Figure 3. Cross-Section for DDH 25ODD-122w

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Table 1. Assay Results for Hole 25ODD-122W*

*Estimated true widths at Gilt Creek are 75-85%. Cut-off grade 1.5 g/t Au with maximum 5.0m internal dilution is applied. Grades are uncapped. * Lower cutoff grade applied to include multiple zones.

Table 2. Drill Hole Coordinates

Quality Control

Omai maintains an internal QA/QC program to ensure sampling and analysis of all exploration work is conducted in accordance with best practices. Certified reference materials, blanks and duplicates are entered at regular intervals. Samples are sealed in plastic bags.

Drill core samples (halved-core) were shipped to Act Labs a certified laboratory in Georgetown Guyana, respecting the best chain of custody practices. At the laboratory, samples are dried, crushed up to 80% passing 2 mm, riffle split (250 g), and pulverized to 95% passing 105 μm, including cleaner sand. Fifty grams of pulverized material is then fire assayed by atomic absorption spectrophotometry (AA). Initial assays with results above 3.0 ppm gold are re-assayed using a gravimetric finish. For samples with visible gold, two separate 250g or 500g pulverized samples are prepared, with 50 grams of each fire assayed by atomic absorption spectrophotometry, with assays above 3.0 ppm gold being re-assayed using a gravimetric finish. Certified reference materials and blanks meet with QA/QC specifications.

For hole 25ODD-122 and 122w, all samples with fire-assay of >0.5 g/t were selectively analysed at ActLabs by Metallic Screening, a technique to more accurately measure gold, especially samples with coarse or visible gold. A representative 500-gram sample split is sieved at 125 μm, with standard fire assays (FA) performed on the entire +125 μm fraction and two splits of the -125 μm fraction. When assays have been completed on the coarse and fine portions of the large sample, a final assay is calculated based on the weight of each fraction. This process provides a more representative total grade than standard 50g FA alone.

Qualified Person

Elaine Ellingham, P.Geo., is a Qualified Person (QP) under National Instrument 43-101 "Standards of Disclosure for Mineral Projects" and has approved the technical information contained in this news release. Ms. Ellingham is a director and officer of the Company and is not considered to be independent for the purposes of National Instrument 43-101.

ABOUT OMAI GOLD

Omai Gold Mines Corp. is a Canadian gold exploration and development company focused on rapidly expanding the two orogenic gold deposits at its 100%-owned Omai Gold Project in mining-friendly Guyana, South America. The Company has established the Omai Gold Project as one of the fastest growing and well-endowed gold camps in the prolific Guiana Shield. In August 2025, the Company announced a 96% increase to the Wenot Gold Deposit NI 43-101 Mineral Resource Estimate¹ (MRE) to 970,000 ounces of gold (Indicated) averaging 1.46 g/t Au, contained in 20.7 Mt and 3,717,000 ounces of gold (Inferred MRE) averaging 1.82 g/t Au, contained in 63.4 Mt. This brings the global MRE at Omai, including the Wenot and adjacent Gilt Creek deposits, to 2,121,000 ounces of gold (Indicated MRE) averaging 2.07 g/t Au in 31.9 Mt and 4,382,000 ounces of gold (Inferred MRE) averaging 1.95 g/t Au in 69.9 Mt. A baseline PEA announced in April 2024, contemplated an open pit-only development scenario and included less than 30% of the new Mineral Resource Estimate for Omai. Five drills are currently active on the property: at Wenot the focus is to optimize the upcoming PEA, to further test the limits of the deposit, including both east and west, and to commence upgrading the large Inferred MRE to Indicated. Additional drilling will continue to explore certain known gold occurrences for possible near-surface higher-grade satellite deposits. An updated PEA is planned for H1 2026 to include the expanded Wenot open pit deposit and the adjacent Gilt Creek underground deposit. The Omai Gold Mine produced over 3.7 million ounces of gold from 1993 to 2005², ceasing operations when gold was below US$400 per ounce. The Omai site significantly benefits from existing infrastructure and is connected to the two largest cities in Guyana, Georgetown and Linden.

¹ NI 43-101 Technical Report dated October 9, 2025 titled "UPDATED MINERAL RESOURCE ESTIMATE AND TECHNICAL REPORT ON THE OMAI GOLD PROPERTY, POTARO MINING DISTRICT NO.2, GUYANA" was prepared by P&E Mining Consultants Inc. and is available on www.sedarplus.ca and on the Company's website.

² Past production at the Omai Mine (1993-2005) is summarized in several Cambior Inc. documents available on www.sedarplus.ca, including March 31, 2006 AIF and news release August 3, 2006.

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 release.

Cautionary Note Regarding Forward-Looking Statements

This news release includes certain "forward-looking statements" under applicable Canadian securities legislation. Forward-looking statements include, but are not limited to, statements with respect to the timing of completion of the drill program, and the potential for the Omai Gold Project to allow Omai to build significant gold Mineral Resources at attractive grades, and forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable, are subject to known and unknown risks, uncertainties and other factors which may cause the actual results and future events to differ materially from those expressed or implied by such forward-looking statements. Such factors include, but are not limited to general business, economic, competitive, political and social uncertainties; delay or failure to receive regulatory approvals; the price of gold and copper; and the results of current exploration. Further, the Mineral Resource data set out in this news release are estimates, and no assurance can be given that the anticipated tonnages and grades will be achieved or that the indicated level of process recovery will be realized. There can be no assurance that forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

Cautionary Note Regarding Mineral Resource Estimates

Until mineral deposits are actually mined and processed, Mineral Resources must be considered as estimates only. Mineral Resource Estimates that are not Mineral Reserves have not demonstrated economic viability. The estimation of Mineral Resources is inherently uncertain, involves subjective judgement about many relevant factors and may be materially affected by, among other things, environmental, permitting, legal, title, taxation, socio-political, marketing, or other relevant risks, uncertainties, contingencies and other factors described in the Company's public disclosure available on SEDAR+ at www.sedarplus.ca. The Inferred Mineral Resource in this estimate has a lower level of confidence than that applied to an Indicated Mineral Resource and must not be converted to a Mineral Reserve. It is reasonably expected that the majority of the Inferred Mineral Resource could be upgraded to an Indicated Mineral Resource with continued exploration. The accuracy of any Mineral Resource Estimates is a function of the quantity and quality of available data, and of the assumptions made and judgments used in engineering and geological interpretation, which may prove to be unreliable and depend, to a certain extent, upon the analysis of drilling results and statistical inferences that may ultimately prove to be inaccurate. Mineral Resource Estimates may have to be re-estimated based on, among other things: (i) fluctuations in mineral prices; (ii) results of drilling, and development; (iii) results of future test mining and other testing; (iv) metallurgical testing and other studies; (v) results of geological and structural modeling including block model design; (vi) proposed mining operations, including dilution; (vii) the evaluation of future mine plans subsequent to the date of any estimates; and (viii) the possible failure to receive required permits, licenses and other approvals. It cannot be assumed that all or any part of a "Inferred" or "Indicated" Mineral Resource Estimate will ever be upgraded to a higher category. The Mineral Resource Estimates disclosed in this news release were reported using Canadian Institute of Mining, Metallurgy and Petroleum Definition Standards for Mineral Resources and Mineral Reserves (the "CIM Standards") in accordance with National Instrument 43-101- Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators ("NI 43-101").

Cautionary Statements to U.S. Readers

This news release uses the terms "Mineral Resource", "Indicated Mineral Resource" and "Inferred Mineral Resource" as defined in the CIM Standards in accordance with NI 43-101. While these terms are recognized and required by the Canadian Securities Administrators in accordance with Canadian securities laws, they may not be recognized by the United States Securities and Exchange Commission. The "Mineral Resource" Estimates and related information in this news release may not be comparable to similar information made public by U.S. companies subject to the reporting and disclosure requirements under the United States federal securities laws and the rules and regulations thereunder.

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