Slide 1: Bramaderos Gold-Copper Open Pit Scoping Study
Bramaderos Gold-Copper Open Pit Scoping Study Investor Presentation 21 April 2026 sunstonemetals.com.au ASX: STM
Slide 2: Disclaimer
Disclaimer DISCLAIMER resources, and there is no certainty that further exploration work will result in the determination To the maximum extent permitted by law, no representation, warranty or undertaking, express or of indicated mineral resources or that the production target will be realised. Suns
Slide 3: Bramaderos Scoping Study Outcomes
Bramaderos Scoping Study Outcomes Scoping Study demonstrates clear path to multi-decade, multi-million- ounce gold-copper production centre with immense growth potential 1. Predictable, low-risk gold-copper-silver porphyry geology 2. 23-year mine, 135kozpa AuEq in first 8 years, AISC US$1,499/oz 3.
Slide 4: Bramaderos Scoping Study Highlights
Bramaderos Scoping Study Highlights Mine Schedule Mining Physicals SABC-float-leach processing 1.4 strip ratio 85% Gold / 75% Copper 220 MT at 0.44g/t AuEq 10 Mpta throughput recoveries Single open pit mine 23 year life of mine Designed/costed by Ausenco Gold-equivalent output All In Sustaining Cost
Slide 5: Next steps and unlocking significant growth potential
Bramaderos Scoping Study Highlights 1. Project optimisation and advancement • Commencement of PFS workstreams in 2026/27 Next steps and • Continued metallurgical testing program to optimise flowsheet and recoveries 2. Mineral Resource growth unlocking significant • Opportunity to convert Bramaderos
Slide 6: Nov-25 Mineral Resource update
1. Nov-25 Mineral Resource1 update High-tonnage, near-surface Mineral Resource at Brama-Alba-Melonal with depth extensions and nearby targets ready for drilling Hills in background 1 • The Bramaderos cluster of gold-copper mineralised deposits at surface now covers an area of 2km x 1.8km • 31% of ma
Slide 7: Scoping Study Outcomes
2. Scoping Study Outcomes “The Scoping Study confirms that Bramaderos is set to generate outstanding financial returns underpinned by low operating costs, strong production rates and a 23-year mine life. “The study is based on the existing resource of 3.6Moz of gold- equivalent. And while this is cl
Slide 8: Mining and processing detail
2. Mining and processing detail Mineralisation at surface with minimal pre-strip • Predictable, low- risk porphyry geology • Single open pit schedule of 220Mt at 0.44/t AuEq for 3.1Moz AuEq of contained gold • Very low mining strip ratio of 1.4:1 • Minimal mining dilution due to porphyry geology 8 A
Slide 9: Industry-standard flowsheet
2. Industry-standard flowsheet Attractive metallurgy supports SABC-float-leach process plant Single-line mill throughput of 10Mtpa with potential for future expansion once in production Flotation of copper sulphide and gold orebody followed by cyanide leaching of 100% rougher tail. Limited reage
Slide 10: Summary of physicals
2. Summary of physicals Prioritisation of higher grade delivers ave. 135kozpa AuEq in first 8 years Bramaderos Project Physicals Unit Value Stripping ratio w/o 1.4 Mined material - AuEq LOM Moz 3.1 Mined grade – AuEq LOM g/t Au 0.44 Ave. production – AuEq LOM Kozpa 120 Gold recovery - Ave. LOM % 85
Slide 11: Summary cost analysis
2. Summary cost analysis Superior mining conditions deliver a low capex, low opex Au-Cu Project • Ausenco prepared the process Bramaderos Project Costs Unit Value plant capex and processing costs Development capital US$M 511 • Site benefits from existing road, Life of mine sustaining capital US$M 44
Slide 12: Development pathway
2. Development pathway Project development milestones 12 ASX:STM
Slide 13: Detailed financial outcomes
2. Detailed financial outcomes Low-cost/highly-profitable gold-copper project with immense upside Project Economics at commodity price Base Case Spot Case Gold Price US$/oz 3,500 5,000 Copper Price US$/lb 5.00 6.00 Silver Price US$/oz 50 80 AISC after by-product credits US$/oz 1,499 1,359 Pre-tax NP
Slide 14: Sensitivity analysis
2. Sensitivity analysis Compelling economics with leverage to gold-copper-silver prices Bramaderos US$/oz gold price sensitivity (copper, silver price steady) Pre-tax $3,000 $3,500 $4,000 $4,500 $5,000 $5,500 $6,000 NPV7.5% US$B 0.9 1.4 1.8 2.3 2.7 3.2 3.6 IRR % 30 39 48 57 66 75 83 LOM FCF US$B 2.5
Slide 15: Ecuador – Our Cost Advantage
2. Ecuador – Our Cost Advantage Ecuador has two world-class, lowest cost-quartile 1 operating mines • Fruta del Norte Gold Mine (Lundin Gold) • Mirador Copper Mine (Chinese-owned) Low mining input costs are a competitive advantage • Energy and Labour are both significantly lower than Australia and c
Slide 16: Rapid payback (19 months at Spot)
2. Rapid payback (19 months at Spot) Project generates strong annual cash flows at Base Case gold price of US$3,500/oz 16 ASX:STM
Slide 17: Focus on high-margin ounces
2. Focus on high-margin ounces Mining conditions and Ecuador cost advantage deliver high-margin ounces 1 1: Source – company 31 December 2025 Quarterly Reports. Refer slide 33 for further details. 17 ASX:STM
Slide 18: Immense growth potential
3. Immense growth potential Bramaderos Project, Au-Equivalents (Moz’s) 2 Potential to deliver further MRE growth by converting a portion of 3 the Exploration Target through further drilling 1 New discovery New 113m @ discovery24:: @ 0.64g/t 0.64g/t AuEq AuEq A larger Mineral Resource >6Moz’s would u
Slide 19: Our Strategy
Two potential We have the necessary large, long-life, skillsets to execute low-AISC assets Tier 1 projects High Quality Our Strategy Gold-Copper Assets With the Right People Crafting our advantage Prioritise In the Right value Commodities realisation Resource growth, scalable development, Copper Gol
Slide 20: Bramaderos: A Low-Risk Development
Bramaderos: A Low-Risk Development 1. Predictable, low-risk geology Cluster of gold-copper-silver porphyry systems at surface • pit-constrained 3.6Moz Au-Eq Mineral Resource • rapid resource conversion potential for 5.0M – 12.9Moz AuEq Exploration Target • mineralisation is consistent and predicta
Slide 21: El Palmar: Uncovering the next Giant
El Palmar: Uncovering the next Giant Significant gold-copper deposit Mineral Resource estimate 1.2Moz AeEq1 • Drilling totaling 17,699m completed to date • Three targets defined, with T2 and T3 both extending at depth beyond 1,750m • Deep drilling at T3 delivers results such as 251m @ 0.56g/t AuEq c
Slide 22: Our Experienced Team
Our Experienced Team BOARD OF DIRECTORS MANAGEMENT TEAM Patrick Duffy Dr Bruce Rohrlach Managing Director & CEO General Manager - Exploration Ex-Red 5, Glencore and Xstrata, Mr Duffy brings international Ex-WMC, Intrepid and SolGold, Dr Rohrlach has been part of leadership and capital markets experi
Slide 23: Our Strategy: Value realisation catalysts 2026
Value realisation catalysts 2026 1. Resource growth Exploration drilling ongoing at Copete-Porotillo • Targeted drilling at Melonal • Upgrade Bramaderos 3.6Moz Au-Eq Mineral Resource Our • Evaluating Limon high-grade epithermal options • El Palmar surface exploration activities Strategy 2. Scalable
Slide 24: Significant room for value appreciation
Significant room for value appreciation ASX STM Shares on Issue 226.8M1 Market Capitalisation A$86.2M2 Cash and Equities A$7.8M3 Enterprise value A$78.4M Outstanding options (in-the-money) 8.8M5 Share ownership 1 A 30-1 share consolidation was completed in February 2026. 2 Based on share price of $0
Slide 25: Call Email Web
CALL EMAIL WEB ASX:STM +61 3 7044 2627 info@sunstonemetals.com.au sunstonemetals.com.au
Slide 26: Our Community Focus
Our Community Focus Sunstone appreciates the strong community support that it has at its projects and takes its environmental, social and governance issues very seriously. Inaugural Sunstone Sustainability Report released 27 November 2023 • Significant environmental monitoring programs across all pr
Slide 27: Resource Overview
Resource Overview Sunstone has an advanced portfolio of exploration projects in Ecuador. The portfolio comprises: 1. The Bramaderos Gold-Copper Project Sunstone owns an 87.5% interest, and SolGold Canada, Inc. (formerly Cornerstone Capital Resources) a subsidiary of SolGold, holding 12.5% (loan carr
Slide 28: Resource Overview
Resource Overview Sunstone has an advanced portfolio of exploration projects in Ecuador. The portfolio comprises: 2. The El Palmar Gold-Copper Project Sunstone holds 74.5% of the highly prospective 800ha El Palmar gold-copper porphyry project in Ecuador. Sunstone can acquire 100% through a Staged Ac
Slide 29: Competent Person Statement
Competent Person Statement Competent Persons Statement - Bramaderos The information in this report that relates to Mineral Resources is based on information compiled by Mr Rob Spiers. Mr Rob Spiers is a full-time employee of Spiers Geological Consultants (SGC) and is a Member of the Australasian Ins
Slide 30: Information on Exploration Targets
Information on Exploration Targets Bramaderos On the basis of the extensive surface and sub-surface geochemical datasets at Porotillo and Copete, two domains The Bramaderos porphyry Exploration Target within the Bramaderos concession is estimated from 5 areas – the were identified where there is coh
Slide 31: Information on Exploration Targets (continued)
Information (continued) on Exploration Targets Limon epithermal El Palmar The Limon epithermal Exploration Target was estimated on target prospects where there was a combination of The Exploration Target within the El Palmar concession is estimated from within the T1, T2 and T3 areas. diamond drilli
Slide 32: Peer Comparison Data (page 24)
Peer Comparison Data (page 24) Ordinay Fully Mineral ASX Share price Paid Shares Date of Market Cap Enterprise Resource EV/ Ticker Company Name ($/share)* on issue (M) Appendix 2A ($M) Net Debt Value Moz AuEq Oz AUEq Comments STM Sunstone Metals 0.380 227 18-Mar-26 86 (8) 78 4.8 16 Net Debt Source:
Slide 33: AISC & Production comparison (page 17)
AISC & Production comparison (page 17) AISC Gold Production Operation Company (A$/oz) (koz Au) Karlawinda Capricorn Metals 1,626 126 Mt Magnet Ramelius Resources 1,901 201 Mungari Evolution Mining 2,052 178 Bramaderos Sunstone Metals 2,141 120 Telfer Greatland Resources 2,176 334 Cowal Evolution Min