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OceanaGold Provides Exploration Update for Wharekirauponga, Haile and Didipio

Exploration Programs

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13 DECEMBER 2022 News Release

OceanaGold Provides Exploration Update for Wharekirauponga, Haile

and Didipio

(VANCOUVER, B.C.) OceanaGold Corporation (TSX: OGC) (“OceanaGold” or the “Company”) is pleased

to announce results from the 2022 resource conversion program at Wharekirauponga in New Zealand and

Haile in the United States, and the resource growth program at Didipio in the Philippines.

Gerard Bond, President & CEO of OceanaGold said, “ Our 2022 drill programs delivered strong results,

supporting our focus on creating value through near -mine resource conversion and growth . At

Wharekirauponga, conversion drilling continues to define outstanding intercepts within the high-grade East

Graben Vein Zone. Notably, our drilling to date has defined only a portion of the East Graben Vein Zone

which remains open in multiple directions and, with two parallel veins having seen limited follow-up drilling,

highlights the tremendous upside potential of this outstanding deposit. Haile exploration focused on

conversion and expansion of the resource at Palomino, with the objective of enabling resource growth and

profitable mine life extension. At Didipio, the discovery of two new mineralized structures outside of the

existing resource represents potential upside to our current mine plan and will be a key focus area for the

exploration program in 2023.”

Highlights from the Company’s 2022 resource conversion and growth programs are summarized below.

Waihi, Wharekirauponga resource conversion drilling (estimated true width):

• 73.4 g/t Au and 133.0 g/t Ag over 12.9 m from 448.7 m, East Graben (“EG”) Vein, (WKP109)

• 52.8 g/t Au and 136.2 g/t Ag over 11.8 m from 445.7 m, EG Vein Zone, (WKP115)

• 44.4 g/t Au and 97.8 g/t Ag over 9.8 m from 488.8 m, EG Vein, (WKP107A)

• 17.7 g/t Au and 38.4 g/t Ag over 10.5 m from 405.3 m, EG Hanging Wall Splay, (WKP112)

• 25.9 g/t Au and 42.9 g/t Ag over 5.2 m from 354 m, EG Hanging Wall Splay (WKP116)

Haile, Palomino resource conversion and expansion drilling (downhole length):

• 6.83 g/t Au over 100.6 m from 410.2 m (DDH1121)

• 5.43 g/t Au over 73.2 m from 395.1 m (DDH1142)

• 4.46 g/t Au over 83.1 m from 349.2 m (DDH1119)

• 4.60 g/t Au over 61.7 m from 421.5 m (DDH1125)

Didipio underground resource growth drilling (downhole length):

• 1.90 g/t AuEq (0.87 g/t Au and 0.74% Cu) over 54.3 m from 4.7 m (RDUG449)

• 2.83 g/t AuEq (1.27 g/t Au and 1.12% Cu) over 40.4 m from 3.6 m (RDUG450)

• 3.74 g/t AuEq (1.91 g/t Au and 1.32% Cu) over 30.0 m from 4.0 m (RDUG453)

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Wharekirauponga 2022 Drill Program

The Wharekirauponga low sulphidation epithermal Au-Ag vein system is located approximately 10 kilometres

to the north of the Company’s Waihi Gold Mine. Wharekirauponga hosts an existing Indicated Resource of

1.5 million tonnes grading 13.5 grams per tonne gold (“g/t Au”) and 26.6 grams per tonne silver (“g/t Ag”) for

0.64 million ounces of gold and 1.26 million ounces of silver within the East Graben Vein (“EG”). Inferred

Resources total 2.3 million tonnes at a grade of 9.4 g/t Au and 2 1.8 g/t Ag for 0.70 million ounces of gold

and 1.62 million ounces of silver, with more than 80% of the Inferred Resource contained within the EG and

two high-grade footwall veins (collectively, the “EG Vein Zone”) (see R & R Annual Statement, March 31,

2022).

Since the March 2022 mineral resource estimate, 5,829 meters (“m”) has been drilled at Wharekirauponga,

predominantly on resource conversion of the EG Vein Zone, in addition to a further 679 m supporting

geohydrological and geotechnical studies. Results are in -line with expectations and are anticipated to

increase confidence in the geological and grade continuity of the deposit . Best intersections from the EG

Vein include:

• 73.4 g/t Au and 133.0 g/t Ag over 12.9 m from 448.7 m, EG Vein, (WKP109)

• 52.8 g/t Au and 136.2 g/t Ag over 11.8 m from 445.7 m, EG Vein Zone, (WKP115)

• 44.4 g/t Au and 97.8 g/t Ag over 9.8 m from 488.8 m, EG Vein, (WKP107A)

• 17.7 g/t Au and 38.4 g/t Ag over 10.5 m from 405.3 m, EG Hanging Wall Splay, (WKP112)

• 25.9 g/t Au and 42.9 g/t Ag over 5.2 m from 354 m, EG Hanging Wall Splay (WKP116)

Resource conversion and extensional drilling continues with approximately 2,500 m scheduled for H1 2023

in support of a pre -feasibility study that is expected to be completed around the end of 2023. An Indicated

Resource of 1 .1 million ounces has been determined as the optimal resource size for defining the initial

development plans for the project study work, without limiting improved mine design and/or resource growth

opportunities.

The EG Vein Zone remains the primary, near-term target for drilling with a focus on resource conversion and

growth. The southern shoot of the EG and hanging wall splay is currently defined by multiple high-grade

intercepts with opportunities for both up and down -dip and along strike extension. Step-out drilling in hole

WKP100 (previously released) has also confirmed the EG continues along strike ~200 m to the southwest.

This along strike opportunity provides up -dip potential within the currently recognised window of

mineralisation within the favourable host rhyolite flow. The EG Vein Zone also remains open both to the

southwest and northeast of the curr ently defined 1,200 m strike length. Additionally, the T-Stream and

Western veins have historic intersections ( See November 7, 2019 news release) that remain a focus for

future drilling to understand their potential within the larger Wharekirauponga epithermal system.

Wharekirauponga is part of the Waihi North Project, which has the potential to create significant socio -

economic contributions for the communities in the Coromandel region and for New Zealand. This includes

significant in-country investments and a substantial increase to direct and indirect employment opportunities.

We are envisaging the development of a mine that aligns well with the Company’s commitment to reducing

its carbon footprint . OceanaGold operate s to the highest environmental and social standards which has

enabled it to run a successful and responsible mining business in New Zealand for over three decades. The

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Company has lodged a resource consent application for its proposed Waihi North Project wi th Hauraki

District Council and Waikato Regional Council, and public consultation is expected next year.

For maps and sections see Figures 1-4 and Table 1 for full results.

Figure 1: Location Map showing Waihi Gold Mine and Wharekirauponga Deposit

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Figure 2: Wharekirauponga Plan View of Geology, Drill Traces and Distribution of 3 Main Veins

Figure 3: Long Section on the EG Vein Geology and Gram x Meter Drill Intercepts

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Figure 4: Wharekirauponga Schematic Cross Section Showing Geology and Historical and New

Intercepts (WKP109)

Haile 2022 Palomino Drill Program

At Haile, the Company has defined a pipeline of underground, sediment hosted gold, exploration

opportunities including Horseshoe, Horseshoe Extension and Palomino, all of which occupy similar structural

settings across a strike length of 800 m. This pipeline of exploration targets is now in various stages of

development from Reserves and current underground development (Horseshoe), Indicated and Inferred

Resources (Palomino), and resource definition (Horseshoe Extension).

Based on the 2021 program consisting of 7,046 m in 16 holes, a Palomino resource was reported in March

2022 with an Indicated Resource of 2.3 million tonnes grading 2.79 g/t Au for 0.20 million ounces of gold

and an Inferred Resource of 3.6 million tonnes at a grade of 2.3 g/t Au for 0.26 million ounces of gold1 (see

R & R Annual Statement, March 31,2022).

In 2022, a further 9,977 m in 20 holes having been completed with a focus on converting the remaining

Inferred resource to Indicated in support of an internal economic analysis and an updated resource estimate,

the later expected to be released on March 31, 2023.

The latest program of resource conversion drilling has returned intercepts that have improved confidence in

grade distribution and continuity of mineralisation and in general support the block model. Best intersections

include:

• 6.83 g/t Au over 100.6 m from 410.2 m (DDH1121)

• 5.43 g/t Au over 73.2 m from 395.1 m (DDH1142)

• 4.46 g/t Au over 83.1 m from 349.2 m (DDH1119)

• 4.60 g/t Au over 61.7 m from 421.5 m (DDH1125)

1 The resources are reported within a conceptual stope design using a US$1,700/oz gold price, approximating a 1.39 g/t cut-off grade.

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The style of mineralisation at Palomino is similar to the Horseshoe deposit with wide zones of gold

mineralisation hosted by pyritic and silicified siltstone and intrusive rocks at the meta -volcanic and meta-

sedimentary contact.

For plan view and long section see Figure 5 and 6 and Table 2 for full results.

Figure 5: Plan view of the Haile Gold Mine with the reserve pit outline, open pit and underground

mineralisation footprints and 2022 drill hole traces

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Figure 6: Long Section for the Palomino underground showing geology and drill holes completed

to date (pre-2022 and 2022 with drill hole identification)

Didipio 2022 Drill Program

At Didipio, mining of the alkalic porphyry copper-gold system commenced in 2013 and hosts a 2P Reserve

of 42.2 Mt @ 0.91 g/t Au and 0.35% Cu for 1.23 Moz gold and 0.15 Mt copper , a Measured and Indicated

resource of 47.8 Mt @ 0.92 g/t Au and 0.36% Cu for 1.41 Moz gold and 0.17 Mt copper, and an Inferred

resource of 15 Mt @ 0.9 g/t Au and 0.3% Cu for 0.4 Moz gold and 0.04 Mt copper (see R & R Annual

Statement, March 31, 2022).

Immediately outside the known extents of underground copper -gold mineralisation and within 200 m of

existing mine development, five high-potential copper-gold targets have been identified. Initial drilling of the

first of five targets included 3,852 m and has returned positive results with two previously unknown zones of

mineralisation being intersected; a copper -gold mineralised Feldspar Porphyry intersected in four holes at

the northeast end of the mine and a cemented Monomictic (Eastern) Breccia in five holes. The plan view

extent of the Feldspar Porphyry has been largely defined between 2,200 and 2,400 mRL and the Eastern

Breccia between 2,200 and 2,300 mRL. However, mineralisation remains open vertically. Further drilling is

being prioritised and is required to better define these targets and understand their full potential, however

early results are very encouraging.

Significant intercepts from the Eastern Breccia include:

• 1.90 g/t AuEq (0.87 g/t Au and 0.74% Cu) over 54.3 m from 4.7 m (RDUG449)

• 2.83 g/t AuEq (1.27 g/t Au and 1.12% Cu) over 40.4 m from 3.6 m (RDUG450)

• 3.74 g/t AuEq (1.91 g/t Au and 1.32% Cu) over 30.0 m from 4.0 m (RDUG453)

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Significant intercepts from the Feldspar Porphyry include:

• 2.33 g/t AuEq (1.44 g/t Au and 0.64% Cu) over 23 m from 166.0 m (RDUG442)

• 2.18 g/t AuEq (1.37 g/t Au and 0.58% Cu) over 20 m from 130.0 m (RDUG443)

Drilling of the mineralized feldspar-porphyry intrusion followed an earlier intercept that remained open. Along

with the four drillholes completed to date, the zone of mineralisation extends over a vertical distance of

approximately 250 m and remains open at depth.

Although mine development had not recognised depth extensions of the Eastern Breccia, the source of the

breccia remained in question. Drilling from the 250 m level was therefore undertaken and immediately

intercepted a copper-gold mineralised quartz-breccia up to 48 m wide with a current vertical extent of 75 m

consisting primarily of quartz clasts cemented by chalcopyrite and bornite. Drilling continues to better define

the geometry of the structure, that remains open at depth, and grade continuity.

For maps and sections see Figure 7, 8, 9 and Table 3 for full results.

Figure 7: Plan view of underground development and lithologic units a 2,300 mRL