NEWGEN21-Proceedings-Full

De Grey Mining Exploration




▪ Initial focus on Ni-Cu PGEs

▪ 2003 - discovered Wingina gold deposit, on the TTSZ (15km E of Hemi)


▪ 2005 - discovered VMS mineralisation (Orchard Tank, Discovery etc)


▪ 2005 - discovered T1 (Scooby) prospect – Hemi-style intrusive complex, 2km NE of Hemi

▪ 2006-2007 – fence of aircore holes drilled across Hemi (Eagle) deposit



Drilling prior to 2019

T1/Shaggy (previously drilled 2007)

T1/Scooby






Aquila-Crow
2 holes over Eagle failed Eagle
to penetrate cover (2007)

Brolga
Diucon




Falcon Location 9 or Jacob,

Antwerp drilled in 1988


12
2km

2006-2007 aircore drilling - Eagle












Transported cover
(40m)








“Pebbles blocking

bit, wet samples,
abandon hole”

























13

2021 drilling - Eagle
























































14

De Grey - mountains and snow







▪ Late 2008 - decision to cut holding


costs, pursue other projects


▪ Pilbara gold projects farmed out


▪ IOCG QLD, epithermal gold in

Argentina, NZ, diamonds in Africa




























▪ De Grey 14/06/2012




15

De Grey Mining






▪ Late 2013 – current De Grey Chairman Simon Lill and

CoSec Craig Nelmes join


▪ 2016 – Rugby Mining Ltd withdraw from JV, 100%
ownership back to DEG Aquila-Crow
Eagle
▪ 2016 – De Grey Technical Director Andy Beckwith, and

GM Exploration Philip Tornatora join Brolga

Diucon
▪ Wingina reviewed, recognition of exploration potential

of tenements Falcon
2016 soil
▪ Exploration rejuvenated (regional and deposit) - drilling, traverses
aeromag, airphotos, database compilation

1km
▪ 2016 – Regional soil geochem survey (over Hemi)


▪ Additional tenements acquired including Indee Gold

project in 2017


▪ Resources increased from 0.35Moz to 2.2Moz






16

De Grey Mining









▪ 2017 – Conglomerate gold



▪ 2017 - King Col lithium prospect discovered


▪ Focus still on bedrock gold






































17

Updated geological interpretation




▪ 2018 - Allan Kneeshaw – updated geology interpretation



▪ Toweranna style mineralisation (intrusion-hosted, size potential, free milling, high grade)


▪ DGO investment, encouragement of regional drilling



▪ July 2019 ASX - “Multiple new targets increase exploration potential”






































18

July 2019 – intrusive targets defined, including Hemi


















▪ Hemiphaga ranked 7 th

of 7 intrusive targets



































19

New Target Style?
























▪ De Grey Special Prospectus, 2003
































20

Approvals




▪ Hemi discovery (late 2019) from broad, regional Mt Berghaus West AC program


▪ Heritage



▪ PoW






Mt Berghaus (181Koz)
5km




Proposed AC traverses








Wingina (288Koz)

Hemi








Calvert (52Koz)





21

Mt Berghaus West AC program





▪ During 2018-19 - 48.6km of AC drilling at various prospects



▪ To end 2019 - 19.7km AC at Mt Berghaus West



▪ Drill fences over Hemi were spaced at 640m, with holes 160m apart




Mt Berghaus (181Koz)
5km




Proposed AC traverses








Wingina (288Koz)











Calvert (52Koz)





22

Mt Berghaus West AC program






























AC 4m composites
Reported by lab 15/12/2019
























23

Hemi discovery – finally!




▪ 27/11/2019 – BWAC245 drilled into Aquila. “Juicy” – 43m @ 3.7g/t Au



▪ 29/11/2019 – BWAC258 drilled into Brolga - 25m @ 2.7g/t Au



































17/12/2019

ASX release “New Gold
Discoveries at Hemi and
Antwerp”



24

Hemi – first cross sections




Aquila





























Brolga












17/12/2019. ASX release “New Gold

Discoveries at Hemi and Antwerp”




25

January 2020 – Define dip
























































Aquila – 6/2/2020
26

January 2020 – Next work out strike

























BWAC258




BWAC245

























27

Hemi – first cross sections




Aquila





























Brolga












17/12/2019. ASX release “New Gold

Discoveries at Hemi and Antwerp”




28

Brolga – July 2020






BWAC258


















































29

Hemi – September 2020












BWAC258












































30

Brolga and Aquila





▪ RC followed by diamond drilling commenced late February 2020


▪ 80m x 80m RC at Aquila and Brolga by end May


▪ Analysts predict ~ 0.5Moz (Aquila), 1.5Moz (Brolga)


▪ Crow drilling progressing







































31
HERC001 (Brolga) – 93m @ 3.3g/t Au

Brolga






▪ Wide zones of


consistent grade

mineralisation



▪ Remains open at

depth and to the


west and south































32

Falcon






▪ Aquila SW extension – died out 200m

west of BWAC245


▪ June 2020 - fences extended south



▪ BWAC567-568 – “strong Aquila style

mineralisation” (Sam)


▪ 33m @ 1.5g/t Au and 20m @ 0.9g/t Au


▪ 160m step out fences not successful


▪ Perimeter around intercepts, keep drilling



▪ 80m x 40m before recognised that Falcon

trended N-S


▪ Grid swung around and +1Moz defined

within several months








33

Diucon






▪ July 2020 – 320m x 80m AC fences over

Diucon and Eagle


▪ Holes straddled higher grade zones, no

ore grade intercepts



▪ Geologist (Dimitri) reported felsic

intrusive rocks, PY, ASPY, named prospect

Diucon


▪ Infilled to 160m x 80m, anomalous but

still low level results


▪ Persisted and RC extended west from

Crow defined an intrusive unit over 900m


▪ November 2020 – 99m @ 1.0g/t Au in

HERC382



29/01/2021. ASX release “Diucon and
Eagle: Two new intrusion hosted gold
discoveries at Hemi”
34

Eagle






▪ Mineralised intrusive, moderately

anomalous geochem from general area


▪ November 2020 – IP survey, rig sent away

to low priority area



▪ Two holes drilled both intersected

mineralisation. 68m @ 0.7g/t Au

(HERC377) incl. 6m @ 2g/t Au and 18m

@ 1.3g/t Au (Matt)


▪ Combined JORC maiden resource of

1.45Moz for Diucon-Eagle (drilling to May

2021)


▪ Diucon-Eagle still open







29/01/2021. ASX release “Diucon and
Eagle: Two new intrusion hosted gold
discoveries at Hemi”
35

Hemi Maiden Resource Estimate






▪ 192Mt @ 1.1g/t Au (6.8Moz)


▪ Based on drilling from March 2020 –

May 2021 (15 months)


▪ Rate of ~450koz per month


▪ ~166km RC, 41km DD core



▪ >200km of drilling


▪ 0.3g/t Au cut-off above 370m depth,

1.5g/t Au cut-off below 370m depth


▪ 41% Indicated (higher at shallower

depths)


▪ TOTAL DEG resource 9Moz












36

High Ounces per Vertical Metre










OUNCES PER
DEPOSIT
VERTICAL METRE


Brolga 9,000


Aquila 2,500


Crow 4,000

Falcon 3,800


Diucon/Eagle 6,000


TOTAL Hemi 25,300






▪ Robust nature: 5.6Moz @

1.5g/t Au at 0.7g/t Au cut-off










37

Mallinaproject scoping study (Oct 2021)




Input Parameters
▪ Plant throughput 10Mtpa


▪ Average processing recovery of 93%, Hemi strip ratio 4.8:1
▪ A$835M – plant/infrastructure capital (incl 25% contingency), AUD58M for prestrip





Output Parameters

▪ Average annual production of 473koz over the first five years and 427koz over 10 years

▪ Average AISC of A$1,111/oz over the first five years and A$1,224/oz over 10 years

▪ Pre-tax NPV 5% of A$2.8b, pre-tax IRR of 60% and pre-tax unleveraged payback of 1.5 years

▪ Places project in top five Australian gold mines, top three global gold development project


(based on average annual output)




















38

Hemi Geology




▪ Hemi - intrusion related gold deposit


▪ Various phases of diorite to quartz diorite intrusions

▪ Intruded into Mallina Formation sediments, hornfelsed


▪ 25m – 40m of transported cover over Hemi


▪ Weathering from 20m – 120m deep













Sediments Intrusive

0.06g/t Au 1.13g/t Au



















39
HERC408D – Falcon HW contact

Hemi Geology






▪ Gold mineralisation with stringer and disseminated sulphides (ASPY, PY)



▪ Strong gold – arsenic – sulphur association



▪ Albite, biotite, chlorite and carbonate (calcite) alteration


▪ Anomalous As, Ag, Bi, Mo, Sb, Sn, Te, Zn




























Aquila - HERC042D 173.5m

(3.9g/t Au)



40

Hemi Geology

























































Brolga – HEDD022 111m 41

Hemi Geology






▪ Quartz-sulphide vein overprint in places (McLeod Lode, Diucon-Eagle), VG, sericite alteration

▪ Orogenic overprint?


































Diucon - HEDD060 71m








Eagle – HERC820D 222m

42

Hemi – Schematic cross section


























































43

Geophysics






▪ Aeromagnetics



▪ Gravity



▪ IP – Dipole Dipole and

Gradient Array



▪ Seismic? Crow Brolga






Diucon


Falcon




















44

Contributing factors – Pre-discovery






• Updated compilation and validation of all available exploration data



• Knowledge from previous exploration on a regional and deposit scale (eg. Toweranna)


• Updated geological interpretation and targeting



• Strong board support - funding and encouragement of regional exploration, focus on drilling



• Large scale heritage surveys clearing large areas for grass roots exploration


• Importance of effective drilling and sampling, over broad areas



• Importance of scale






















45

Contributing factors – Syn-discovery






• Data capture and validation procedures reasonably streamlined and effective


• Early recognition of “Hemi-style” lithologies, alteration and mineralisation by rig geologists



• pXRF for As - allowed rapid follow up drilling before assays back


• Pre-existing relationships with drilling and assay companies



• Minimal Covid impact in WA



• Detailed geochem analysis – assist targeting at both regional and deposit scale


• Drill, drill, drill. Since Jan 2020 – 330km AC, 274km RC, 70km DD core























46

The Hunt for the next Hemi






▪ Geophysics and geochemistry


utilised to target prospective areas


▪ Identify new, mineralised intrusives

with wide-spaced aircore



▪ Test prospective areas with RC and

diamond drilling



▪ Step out and test along strike and

down dip of mineralisation



▪ Potential for mineralised intrusive

below sediments with minimal

anomalism












47

Looking ahead – MallinaProject





▪ Prefeasibility Study underway


▪ Hemi deposits still remain open, particularly at depth


▪ Numerous targets across tenements – Intrusion and shear-hosted


▪ Very low discovery cost of ~$8.50 per resource ounce


▪ Drilling ongoing (12-14 rigs) - Hemi, Greater Hemi and Regional



▪ Looking forward to adding ounces and the next discovery






























48

Metallurgy






▪ Flotation to recover sulphide concentrate


(8% feed mass)



▪ Oxidation by pressure oxidation (POX),

bacterial oxidation (BIOX®), or ultra-fine

grinding (Albion®).



▪ Oxide samples are free milling, can bypass

the flotation and oxidation circuits



▪ 92.5% gold recoveries overall to date






















49

ConceptualProject Schedule









2021 2022 2023 2024 2025



Ongoing drilling




Mineral Resource update




Pre-Feasibility Study




Definitive Feasibility Study



Development
application assessment



Construction phase




Production/operational phase






50

Wharekirauponga


A low-sulphidation


epithermal gold-silver

discovery in New Zealand




NewGen Gold Conference

November 2021

2

Cautionary and Technical Statements



Cautionary Notes -Information Purposes Only
The information contained in this presentation is provided by OceanaGold Corporation (“OGC”) for informational purposes only and does not constitute an offer to issue or arrange to issue, or the
solicitation of an offer to issue, securities of OGC or other financial products. The information contained herein is not investment or financial product advice and has been prepared without taking into
account the investment objectives, financial situation or particular needs of any particular person. The views, opinions and advice provided in this presentation reflect those of the individual presenters only.
No representation or warranty, express or implied, is made as to the fairness, accuracy, completeness or correctness of the information, opinions and conclusion contained in this presentation, except as
otherwise required by law. To the maximum extent permitted by law, none of OGC or any of its directors, officers, employees or agents accepts any liability, including, without limitation, any liability arising
out of fault or negligence, for any loss arising from the use of the information contained in this presentation. Furthermore, this presentation does not constitute an offer of shares for sale in the United
States or to any person that is, or is acting for the account or benefit of, any U.S. person (as defined in Regulation S under the United States Securities Act of 1933, as amended (the "Securities Act")) ("U.S.
Person"), or in any other jurisdiction in which such an offer would be illegal. OGC’s shares have not been and will not be registered under the Securities Act.

Cautionary Statement Concerning Forward Looking Information
Certain information contained in this presentation may be deemed “forward-looking” within the meaning of applicable securities laws. Forward-looking statements and information relate to future
performance and reflect OGC’s expectations regarding the generation of free cash flow, execution of business strategy, future growth, future production, estimated costs, results of operations, business
prospects and opportunities of OGC and its related subsidiaries. Any statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives,
assumptions or future events or performance (often, but not always, using words or phrases such as “expects” or “does not expect”, “is expected”, “anticipates” or “does not anticipate”, “plans”,
“estimates” or “intends”, or stating that certain actions, events or results “may”, “could”, “would”, “might” or “will” be taken, occur or be achieved) are not statements of historical fact and may be forward-
looking statements. Forward-looking statements are subject to a variety of risks and uncertainties which could cause actual events or results to differ materially from those expressed in the forward-looking
statements and information. They include, among others, the accuracy of mineral reserve and resource estimates and related assumptions, inherent operating risks, and those risk factors identified in
OGC’s most recent annual information forms prepared and filed with securities regulators which are available on SEDAR at www.sedar.com under OGC’s name.
There are no assurances OGC can fulfil forward-looking statements and information. Such forward-looking statements and information are only predictions based on current information available to
management of OGC as of the date that such predictions are made; actual events or results may differ materially as a result of risks facing OGC, some of which are beyond OGC’s control. Although OGC
believes that any forward-looking statements and information contained in this presentation are based on reasonable assumptions, readers cannot be assured that actual outcomes or results will be
consistent with such statements. Accordingly, readers should not place undue reliance on forward-looking statements and information. OGC expressly disclaims any intention or obligation to update or
revise any forward-looking statements and information, whether as a result of new information, events or otherwise, except as required by applicable securities laws. The information contained in this
release is not investment or financial product advice.

Technical Disclosure
Mineral Resources for Waihi have been verified and approved by or are based upon information prepared by or under the supervision of, P. Church. Information relating to Waihi exploration results in this
presentation has been verified by, is based on and fairly represents information compiled by or prepared under the supervision of L. Torckler. Mine Designs and schedules for Waihi have been verified and
approved by or are based upon information prepared by or under the supervision of, T. Maton. Metallurgical and mineral processing information for Waihi has been verified and approved by or are based
upon information prepared by or under the supervision of, D. Carr. D. Carr, P. Church, and T. Maton are Members and Chartered professionals with the Australasian Institute of Mining and Metallurgy while
L. Torckler is a Fellow with the Australasian Institute of Mining and Metallurgy. Messrs Carr, Church, Maton and Torckler have sufficient experience, which is relevant to the style of mineralisation and type
of deposits under consideration, and to the activities which they are undertaking, to qualify as Competent Persons as defined in the 2012 Edition of the “Australasian Code for Reporting of Exploration
Results, Mineral Resources and Ore Reserves” (“JORC Code”) and all are Qualified Persons for the purposes of the NI 43 101. Messrs Carr, Church, Maton and Torckler are employees of OceanaGold and
they consent to the inclusion in this public presentation of the matters based on their information in the form and context in which it appears. For further scientific and technical information (including
disclosure regarding Mineral Resources and Mineral Reserves) relating to the WKP Project please refer to technical reports available at sedar.com under the Company’s name.

3














CONTENTS






1. Location & Setting

th
2. 19 Century Exploration

3. 20 Century Exploration
th
4. 21 Century Exploration
st
i. Discovery time
ii. Drilling

iii. Resources


5. Future Mine

6. Conclusions


7. Questions

Wharekirauponga (WKP) Gold Project 4



A low-sulphidation epithermal Au-Ag discovery in New Zealand


Hauraki Goldfield


• 200km by 40km Epithermal Vein Province

• >50 known gold deposits


• Produced 1852 - 2020 12.2Moz Au, 53.3Moz Ag


• 92% from 4 camps


• >97% Andesite hosted

Waihi Camp Au Moz Ag Moz

Produced 8.12 45.8

Indicated Resources 1.37 6.0
Incl. Reserves 0.63 2.0

Inferred Resources 0.69 4.2
Thames Camp

Produced 1.44 0.7

Karangahake
Produced 0.95 3.1

Golden Cross

Produced 0.76 2.5

Map of Hauraki Goldfield Geology, Gold Production, OceanaGold Tenements

Wharekirauponga (WKP) Gold Project 5



A low-sulphidation epithermal Au-Ag discovery in New Zealand


Hauraki Goldfield Geological Setting


• Jurassic greywacke & argillite basement

• Overlain by Miocene andesites & dacites


• Intruded, interfingered and overlain by mid - late Miocene rhyolites

• Epithermal vein mineralisation Mid – Late Miocene:

• Youngs southward
• Magmatic arc porphyry-related epithermal gold-silver deposits in the northwest

• Bimodal volcanic rift associated adularia-sericite gold-silver deposits in the central-

southern part of the region.
• More subtle zonation, in part erosional due to a regional SE tilt exposing deeper
levels in the west


• Intruded and overlain by post-mineral Plio-Pleistocene andesites and rhyolites












Near surface indicators: opaline quartz, sinter, fossil flora, chalcedony, vent breccias
Boiling indicators: colloform banding of quartz+chalcedony, lattice-bladed quartz after platy calcite, adularia, chalcedony
Deep boiling: crustiform banding of crystalline quartz
Deep epithermal: crystalline quartz, crustiform banding of base metal sulphides, boxwork & radiating nodular quartz

Wharekirauponga (WKP) Gold Project 6



A low-sulphidation epithermal Au-Ag discovery in New Zealand



Wharekirauponga

• Located 10km north of Waihi


• Crown owned Forest Park administered by
Department of Conservation


• Historical benched horse and cart tracks – paper roads


• Access only on foot ~1.5 hours up valley, or helicopter

Wharekirauponga (WKP) Gold Project 7



A low-sulphidation epithermal Au-Ag discovery in New Zealand


19 Century Exploration
th
1888 Gold discovered


1895-97 Construction


12km tramway from coast

Managers house, offices,

storehouse & assay lab


Township housing 300 men

Prospected by adits and

shafts

Battery site excavated and 40

stamp battery ordered

‘Mining Magnates on Tour. 14 tons treated at Thames
Waihi Russell and Kersey
Cooper, two of the sharpest School of Mines for 19 oz
Upper Thames mining experts, Bullion
leave for the land of bullion to
float off their “big guns.” Gold in
every inch of it’, 1898 All work abandoned as
Observer, 17 August 1895, p 7 the veins intersected were all
of short strike length

Wharekirauponga (WKP) Gold Project 8



A low-sulphidation epithermal Au-Ag discovery in New Zealand




th
20 Century Exploration
1978 Amoco Minerals Gorge Section Wharekirauponga










































Analytic Signal Aeromag
Regional Aeromagnetics Outcropping Gold Mineralised Epithermal Quartz Veins

Wharekirauponga (WKP) Gold Project 9



A low-sulphidation epithermal Au-Ag discovery in New Zealand

1980-82 Amoco Minerals

• Target concept: open pittable resource on outcropping sheeted veins system

• 2,692m drilled in 15 holes, 80% steeper than 75 o

• Broad low grade gold drill intersections with numerous narrow discontinuous high-grade gold
mineralised veins e.g. WKP4

• 150m @ 0.9g/t Au incl. 17.7m @ 4.0g/t Au & 2.3m @ 19.6g/t Au

• Concluded no open pittable resource – refocussed to high grade u/g potential but distracted
by discovery at Golden Cross

1985-88 JV BHP

• Target concept: high grade veins on margin of andesite dyke within rhyolite flow dome
complex

• Ground mag, rock & soil sampling to map out andesite dyke

• 986m drilled in 3 holes returning best intersections of 43m @ 1.1g/t Au and 1m @ 48g/t Au

• Concluded no significant gold mineralised zones

1989-93 JV ACM

• Target concept: exploring for higher grade shoots on lateral extents of the outcropping gorge
mineralisation

• Mapping, rock, soil, BLEG sediment, low level aeromag, CSAMT, gradient array

• 1,837m in 5 holes returning similar results to 104m @ 1.3g/t Au

• Withdrew from JV following takeover by Normandy

Wharekirauponga (WKP) Gold Project 10



A low-sulphidation epithermal Au-Ag discovery in New Zealand




21 Century Exploration
st
2003 HPD NZ Ltd


• May 2003 Exploration Permit 40598, covering WKP,
granted


• Desktop prospectivity with weights of evidence training
dataset


• Relatively low prospectivity probability ranking


• No field work


2002 – 2006 Glass Earth

• Geoinformatics data intervention process


• Targeting and ranking involving evaluation of
concurrent multi-disciplinary information


• WKP prospectivity identified


• March 2006 acquired EP40598 from HPD

• No field work

Wharekirauponga (WKP) Gold Project 11



A low-sulphidation epithermal Au-Ag discovery in New Zealand




21 Century Exploration
st
Newmont


• 2002 acquired Waihi Gold Mine through acquisition of
all Normandy’s assets


• 2005 initiated 18 month long “Framework Study” of
Hauraki Goldfield – similar data intervention and GIS

evaluation process to Glass Earth


• Prospectivity map derived from favourability matrix
calculation supported by weights of evidence identified
WKP as a high priority target to be acquired and

assessed for Martha size deposits


• Feb 2007: Farm In and Operating Agreement with
Glass Earth covering all Glass Earth tenements in the
Hauraki Goldfield including EP40598 over WKP