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Advancing Two Multi-Decade Gold-Copper Projects Investor Presentation Patrick Duffy, MD & CEO 9-10 September 2026 sunstonemetals.com.au ASX: STM
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Disclaimer 2 ASX:STM DISCLAIMER To the maximum extent permitted by law, no representation, warranty or undertaking, express or implied, is made and, to the maximum extent permitted by law, no responsibility or liability is accepted by Sunstone or any of its officers, employees, agents or consultants or any other person as to the adequacy, accuracy, completeness or reasonableness of this Presentation. To the maximum extent permitted by law, no responsibility for any errors or omissions from this Presentation whether arising out of negligence or otherwise is accepted. This Presentation contains general information about Sunstone Metals Limited (Sunstone) which is in the business of exploring for minerals which is a speculative and risky venture. It does not purport to contain all the information that a prospective investor may require. The Presentation should not be considered as an offer or invitation to subscribe for or purchase of any securities in Sunstone and no agreement to subscribe for securities will be entered into on the basis of this Presentation. Potential investors should conduct their own investigation and analysis and should check the accuracy, reliability, and completeness of the information provided and obtain independent and specific advice from appropriate professional advisors. FORWARD-LOOKING STATEMENTS This Presentation includes certain statements that may be deemed “forward-looking statements” . All statements in this Presentation, other than statements of historical facts, that address future activities and events or developments that Sunstone expects, are forward looking statements. Although Sunstone believes the expectations expressed in such forward- looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results or developments may differ materially from those in the forward-looking statements. Factors that could cause actual results to differ materially from those in forward-looking statements include market prices, continued availability of capital and financing, and general economic, market or business conditions. Investors are cautioned that any such statements are not guarantees of future performance and that actual results or developments may differ materially from those projected in forward-looking statements. EXPLORATION TARGETS This presentation contains information on Exploration Targets. The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Resource for the exploration target area reported. It is uncertain if further exploration will result in the estimation of a Resource.
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With the Right People In the Right Commodities Prioritise value realisation High Quality Gold-Copper Assets 3 ASX:STM Our Strategy Crafting our advantage Two potential large, long-life, low-cost assets We have the necessary skillsets to execute Tier 1 projects Resource growth, scalable development, funding pathways Natural complement between Gold and Copper
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Real potential for a world-class asset El Palmar • Major bulk scale deposit at surface in Northern Ecuador • 1.2Moz AuEq2 Maiden JORC Resource1 from top 450m of the T1 target • 15M – 45Moz AuEq3 JORC Exploration Target1 (in addition to MRE) • Immense growth potential along the copper-rich Toachi Fault Our Flagship Assets 100km 4 1 See ASX announcement 22 Oct 2024 2 64Mt at 0.60g/t AuEq for 1.2Moz AuEq 3 1.0 -1.2Bt at grade between 0.3-0.7 g/t Au and 0.1-0.3% Cu 4 220Mt at 0.50g/t AuEq for 3.6oz AuEq Refer to slides 27 to 31 for full JORC details ASX:STM 5 Porphyry: 315-505Mt at grade between 0.30-0.54 g/t Au and 0.09-0.11% Cu Limon: 30-40Mt at grade between 0.8-1.1 g/t Au and 12-15.8g/t Ag Refer to slides 26 to 30 for full JORC details 6 See ASX announcement 24 November 2025 7 See ASX announcements 21 April 2026, 11 May 2026 Large-tonnage, low-cost, ideal location Bramaderos • Cluster of gold-copper-silver porphyry systems extending from surface • 3.6Moz AuEq4 Bramaderos 2025 JORC Resource6 • 5.0M – 12.9Moz AuEq5 JORC Exploration Target6 (in addition to MRE) • Scoping Study released in April 20267
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5 ASX:STM BOARD OF DIRECTORS Our Experienced Team Patrick Duffy Managing Director & CEO Ex-Red 5, Glencore and Xstrata, Mr Duffy brings international leadership and capital markets experience with a successful mine development track record Malcolm Norris Non-Executive Chair Ex-WMC, Intrepid and SolGold, Mr Norris has been part of several major global porphyry discoveries and brings mineral exploration and management expertise Neal O’Connor Non-Executive Director Former Xstrata Copper Chief Legal Counsel, Mr O’Connor has extensive experience developing South American mining operations and infrastructure Stephen Stroud Non-Executive Director Mr Stroud is Director – Corporate Finance at Morgans and brings extensive capital markets knowledge and investor relationships MANAGEMENT TEAM Dr Bruce Rohrlach General Manager - Exploration Ex-WMC, Intrepid and SolGold, Dr Rohrlach has been part of several major porphyry discoveries and oversees all exploration programs at Sunstone Lucas Welsh CFO & Company Secretary Former CFO of St Barbara, Mr Welsh is a specialist resources financial executive with international mining, capital markets and governance expertise Ray Robinson GM – Studies & Tech Services Ex-PanAust, Placer Dome and Intrepid, Mr Robinson has extensive mining studies and operations experience, and oversees all study programs at Sunstone Rodrigo Izurieta Country Manager Based in Quito, Ecuador, and US-educated, Mr Izurieta is highly respected with deep relationships in the local mining industry and government
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Forms part of the worlds most endowed copper gold belt • 2 world-class operating mines – Fruta del Norte Mirador • Majors present (BHP , Newmont, Barrick, CMOC, Jiangxi Copper) Mining Investment Pipeline includes • Silvercorp – El Domo Curipamba Copper/Gold Project • Solaris – Warintza Copper Project • CMOC – Cangrejos Gold Project • Jiangxi/Solgold – Cascabel Copper Project 2025/26 Transaction Highlights Jiangxi Copper A$1.7bn acquisition of Solgold in March 2026 CMOC C$581m acquisition of Lumina Gold in April 2025 100km 6 ASX:STM Ecuador – Rich in Gold and Copper Apr-25 President Noboa re-elected for a four-year term • President actively encouraging responsible mining • Single national mining department 1 1 2 2 3 3 4 4 5 5 6 6 6
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Ecuador has two world-class, lowest cost-quartile 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 in Australia and comparable mining nations • Potential for Sunstone’s projects to be in the lowest cost quartile • Complimented by very low stripping ratios (Bramaderos ratio 1.4) Hydro provides base energy load for the country (>90%) • Potential for low-cost, low-carbon emission mining Ecuador’s currency is USD • Provides protection against inflation 100km 7 Source: 1. https://www.globalpetrolprices.com/ 2. https://www.erieri.com/salary/job/mining-engineer, https://ca.talent.com/salary?job=Mining ASX:STM Ecuador – Our Cost Advantage 1 2
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Strategic demand for tier-1 scale copper assets New copper supply coming from difficult jurisdictions Electrification driving unprecedented copper consumption Increasing M&A from multinational miners for large projects Record high gold prices – up 65% in 2025 Regional conflicts, trade restrictions, ST interest rate risks Shift towards Gold from USD debasement trade Favorable AUD:USD exchange rate lifts value to Sunstone Source: https://www.investing.com/commodities/gold-historical-data Copper Demand and Supply imbalance likely to grow Total copper market balance (2020-2040): 14MMt shortfall Source: S&P Global, 8 January 2026 8 ASX:STM Our Commodity Advantage Gold price US$4,430/oz 4-Sept-26
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Bramaderos Cluster of open pit multi-decade development opportunities Located in an ideal mining location 9 ASX:STM 9sunstonemetals.com.au ASX: STM 9
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Background image is gold-in-soils Potential to deliver further MRE growth by converting a portion of the Exploration Target through further drilling 10 1 220Mt at 0.50g/t AuEq for 3.6Moz AuEq. 2 30-44Mt at grade between 0.9-1.2g/t Au Eq for 0.9-1.7oz AuEq 3 315-505Mt at grade between 0.40-0.74 g/t AuEq for 4.1-11.2Moz AuEq 4 See slides 26 – 30 for full JORC details. ASX:STM New discovery2: 113m @ 0.64g/t AuEq 1 3 2 New discovery4: 113m @ 0.64g/t AuEq Bramaderos: Positioned for rapid growth Bramaderos Project, Au-Equivalents (Moz’s) The Project-wide Total Exploration Target of 5.0 – 12.9Moz AuEq is in addition to the MRE of 3.6Moz AuEq
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Hills in background 111 See ASX announcement 24 November 2025 ASX:STM Bramaderos: Resource to grow rapidly High-tonnage, near-surface Mineral Resource at Brama-Alba-Melonal with depth extensions and nearby targets ready for drilling • Bramaderos 2025 Mineral Resource estimate of 3.6Moz AuEq, complemented by an additional Project-wide Total Exploration Target of 5.0 – 12.9M AuEq1 • The Bramaderos cluster of gold-copper mineralised bodies at surface now covers an area of 2km x 1.8km • Bramaderos 2025 Mineral Resource estimate based on gold price of US$1,800/oz • 31% of material excluded from MRE as outside pit shell • Targeting upgraded Bramaderos MRE later in 2026 Future drilling programs to determine if Nov-25 MRE pit shell extends to Copete-Porotillo (current drilling focus) and potentially form one large open pit operation
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Hills in background 12 1 See ASX announcements 14 April 2026, 4 May 2026, 21 May 2026, 2 June 2026, 2 July 2026, 18 Aug 2026 2 Copete-Porotillo Exploration Target: 135-185Mt at grade between 0.25-0.40 g/t Au and 0.10-0.12% Cu ASX:STM Bramaderos: Copete-Porotillo drilling New Copete-Porotillo Exploration Target: 1.7 – 3.5 Moz AuEq2 Total Bramaderos Exploration Target: 5.0 – 12.9 Moz AuEq3 • Two rigs drilling to a target depth of 200m’s • Campaign will drive rapid inventory growth • All 20 assayed holes to-date have been fully mineralised from surface, including: • 200m at 0.62g/t AuEq; 19m at 1.01g/t AuEq1 • 92m at 0.66g/t AuEq; 20m at 0.91g/t AuEq1 • 196m at 0.62g/t AuEq: 143m at 0.72g/t AuEq1 • Updated Bramaderos MRE planned in the December Quarter 1 3 Porphyry Exploration Target: 315-505Mt at grade between 0.30-0.54 g/t Au and 0.09-0.11% Cu Limon Exploration Target: 30-40Mt at grade between 0.8-1.1 g/t Au and 12-15.8g/t Ag Drill results suggest Bramaderos 3.6Moz AuEq resource will continue to grow, with the potential to enhance the financial returns on the overall project
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Hills in background ASX:STM Limon: Epithermal-Porphyry System 13 Refer ASX announcements 13 December 2022, 9 November 2023, 6 August 2024, 21 August 2024, 24 November 2025
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14 ASX:STM 14sunstonemetals.com.au ASX: STM 14
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Scoping Study Highlights1 ASX:STM 15 • Predictable, low-risk porphyry geology • Very low mining strip ratio of 1.4:1 • Based on November 2025 MRE • Resource will continue to grow rapidly with further drilling Mineralisation at surface with minimal pre-strip 3D rendering of Figures 4 to 7 in ASX announcement 24 November 2025 1 See ASX announcements 21 April 2026 and 11 May 2026 2 See ASX announcement 1 September 2026 Potential resource growth Material upgrade to recoveries 1-Sep 2 : • Gold 85% -> 93% • Copper 75% -> 80%
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16 ASX:STM Bramaderos: Low-Risk Development 1. Predictable, low-risk geology Cluster of gold-copper-silver porphyry systems at surface • current pit-constrained 3.6Moz AuEq Mineral Resource2 • rapid resource conversion potential for 5.0M – 12.9Moz AuEq Exploration Target1 • mineralisation is consistent and predictable Potential for future higher-grade epithermal ore feed 2. Pathway to significant upside Continue to grow the Resource base Undertake met studies and environmental baseline studies to de-risk project 3. Straight-forward, multi-decade mining Low environmental impact • no protected forests • no major river diversions or downstream major population centres Large scale, high-margin open pit mining (900m’s above sea level) Low-cost mining jurisdiction Access to water, grid power and Pan-American Highway Strong support from remote host community seeking jobs and economic development 1 Porphyry ET: 315-505Mt at grade between 0.30-0.54 g/t Au and 0.09-0.11% Cu; Limon ET: 30-40Mt at grade between 0.8-1.1 g/t Au and 12-15.8g/t Ag 2 220Mt at 0.50g/t AuEq for 3.6oz AuEq. Refer to slides 26 to 30 for full JORC details
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17 ASX:STM 17 El Palmar Pursuing a bulk-scale, low-cost Gold-Copper Tier 1 deposit located on the prodigious copper-rich Toachi Fault sunstonemetals.com.au ASX: STM 17
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Tier 1 regional deposits • 2.7Bt Alpala copper-gold porphyry deposit (0.53% CuEq) at Cascabel • 0.53Bt Tandayama-America copper-gold porphyry deposit (0.36% CuEq) at Cascabel • 1Bt Llurimagua copper-moly porphyry deposit (1.0% CuEq) 18 Hancock committed US$120m to earn 49% into JV with state-owned ENAMI in northern Ecuador (adjacent to El Palmar) ASX:STM Highly prospective mineralised district related to the Toachi Fault Zone El Palmar: Surrounded by Giants
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• Drilling totaling 17,699m completed to date • Three targets defined, with T2 and T3 both extending at depth beyond 1,750m • Maiden resource defined from near-surface drilling representing a potential valuable starter pit Significant gold-copper deposit Mineral Resource estimate 1.2Moz AeEq1 Gold and copper Exploration Target of 15M - 45Moz AuEq1 19 ASX:STM • 1.0Bt to 1.2Bt at a grade between 0.3g/t to 0.7g/t gold and 0.1% to 0.3% copper • Contained metal of between 10Moz and 27Moz gold and 1.0Mt to 3.7Mt copper • Immense potential for El Palmar to grow: Based on only three of five identified targets Deep drilling has skirted the interpreted central target zones Potential for copper content to increase 1 See slides 26 – 30 for full JORC details El Palmar: Uncovering the next Giant
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ASX:STM El Palmar: True Tier-1 Scale Potential • Same scale cross-section comparison with the 3Bt Alpala deposit at Cascabel • Depth to top of the main Alpala orebody is ~700m El Palmar strategic advantage to commence as an Open Pit Immense potential for El Palmar to grow into a major Au-Cu deposit • Exploration drilling to commence in Sept-Qtr targeting high- conviction deeper targets • Potential for replicating discovery success at Cascabel and Llurimagua Cu projects 20
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El Palmar: Targeting the deeper system EPDD026 grades suggest the T3 system can deliver very high grades 21 ASX:STM Refer ASX announcements 15 February 2023, 20 June 2023, 11 September 2023 Drill core from EPDD026
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ASX:STM ASX STM Shares on Issue 284.0M1 Market Capitalisation A$56.8M2 Cash and Equities A$11.6M4 Enterprise value A$45.2M Outstanding options 7.0M5 1 284.0M shares on issue. 2 Based on share price of $0.20 on 7 Sept 2026. 3 Source: Company Public MROR Statements and announcements. Share price data as at 7 September 2026. Refer to page 31 for further details. 4 Unaudited cash balance at 30 June 2026 of $1.7M plus cash raised from placement announced on 29 June 2026 of $9.9M. 5 As at 7 Sept 2026. $1.6m options remain with a strike price of $0.225/share; expiring in October 2026. 6 Historical share prices have been adjusted for the Feb-2026 30-1 share consolidation. Mispriced => rerate opportunity Institutional & Family Office, 34% DGR Global, 10% Board & Management, 5% Other, 51% Share ownership 22
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ASX:STM 2026/27 Value-accretive catalysts 23 Current project status Bramaderos • 3.6Moz AuEq Mineral Resource • 5.0 – 12.9Moz AuEq Exploration Target1 (additional) • Apr-26 Scoping Study3 Value-accretive catalysts • Upgrade Mineral Resource late 2026 • Drilling: Melonal / Limon Deep target • Met testwork and environmental baseline program El Palmar • 15 - 45Moz AuEq Exploration Target2 • 1.2Moz AuEq Mineral Resource at surface (potential starter pit opportunity) • Exploration Drilling: unlocking deeper targets • Surface exploration activities to commence at Verde Chico (adjacent to El Palmar, outside Exploration Targets) Global Mineral Resource of 4.8Moz AuEq to be upgraded late 2026 23 1 Porphyry: 315-505Mt at grade between 0.30-0.54 g/t Au and 0.09-0.11% Cu Limon: 30-40Mt at grade between 0.8-1.1 g/t Au and 12-15.8g/t Ag 2 1.0 -1.2Bt at grade between 0.3-0.7 g/t Au and 0.1-0.3% Cu Refer to slides 26 to 30 for full JORC details 3 See ASX announcements 21 April 2026, 11 May 2026
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ASX:STM WEB sunstonemetals.com.au EMAIL info@sunstonemetals.com.au CALL +61 3 7044 2627
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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 November 2023 • Significant environmental monitoring programs across all projects • Involved in various high-impact community programs at Bramaderos and El Palmar • Undertakes considerable training programs across a large range of skills for workers and the communities in which we operate • Sunstone works with the local communities to assist where possible, for example, during the pandemic • Employment and skills development for local communities Drilling is fully permitted and environmentally compliant at Bramaderos and El Palmar 25 ASX:STM Our Community Focus
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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 carried through to start of commercial production). The Bramaderos gold-copper project is located in Loja province, southern Ecuador, and is highly prospective for the discovery of large porphyry gold-copper systems, and high-grade epithermal gold systems. The Bramaderos concession is host to multiple fertile mineralised systems with significant discovery potential. The Brama-Alba porphyry gold-copper-silver deposit, within the Bramaderos concession contains a current Mineral Resource estimate of 220Mt at 0.50g/t AuEq for 3.6Moz gold-equivalent*. In addition to this is the Bramaderos project porphyry gold-copper-silver Exploration Target of between 4.1Moz and 11.2Moz AuEq* within 315 to 505Mt at a grade between 0.41 and 0.68g/t AuEq* (see ASX release dated 24 November 2025). The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource for the target area reported. It is uncertain if further exploration will result in the estimation of a Mineral Resource. An Exploration Target for the Limon epithermal gold-silver deposit was released on 9 November 2023 (also refer to ASX release dated 5 February 2024) consisting of between approximately 30 and 44 million tonnes at a grade of between 0.9 and 1.2g/t AuEq*, for between 0.9 and 1.7mill oz AuEq*. The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource for the target area reported. It is uncertain if further exploration will result in the estimation of a Mineral Resource. The company confirms that it is not aware of any new information or data that materially affects the information included in the original market announcement for the Mineral Resource estimate and Exploration Target referred to above and, that all material assumptions and technical parameters underpinning the estimates continue to apply and have not materially changed. The company confirms that the form and context in which the Competent Person’s findings are presented have not been materially modified from the original market announcement. * The gold equivalent calculation formula for porphyry gold-copper-silver mineralisation is AuEq(g/t) = (Au grade x Au price x Au recov / 31.1035) + (Ag grade x Ag price x Ag recov / 31.1035) + (Cu grade x Cu price x Cu recov / 100)) / (Au price x Au recov / 31.1035). The prices used were US$1,800/oz gold and US$4.50/lb copper and US$22/oz silver. Recoveries are estimated at 88% for gold, 85% for copper, and 60% for silver based on metallurgical studies (see ASX release dated 24 November 2025). * The gold equivalent calculation formula for epithermal gold-silver mineralisation is AuEq(g/t) = Au(ppm) + (Ag (ppm)/82). The prices used were US$1,800/oz gold and US$22/oz silver. Recoveries are estimated at over 90% for gold and 90% for silver from metallurgical studies (see ASX release dated 9 November 2022). In Sunstone’s opinion all the elements included in the metal equivalents calculation have reasonable potential to be recovered and sold. 26 ASX:STM JORC Classification Tonnage (Mt) Au (g/t) Cu (%) Ag (g/t) AuEq (g/t) AuEq* (Mozs) Indicated 40 0.38 0.10 1.26 0.56 0.6 Inferred 190 0.32 0.10 1.14 0.49 2.9 Total 220 0.33 0.10 1.16 0.50 3.6 Resource Overview
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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 Acquisition Agreement. A Staged Acquisition Agreement to acquire the nearby Verde Chico Project has also been signed. The El Palmar and Verde Chico gold-copper projects are located in Imbabura province, northern Ecuador, within the same geological belt that includes the giant Alpala, Tandayama-America and Llurimagua porphyry copper-gold and copper-molybdenum deposits. The El Palmar porphyry gold-copper-silver deposit within the El Palmar concession contains an initial Mineral Resource estimate of 64Mt at 0.60g/t AuEq for 1.2Moz AuEq*. In addition to this is the El Palmar Exploration Target of between 15Moz and 45Moz AuEq* within 1.0Bt to 1.2Bt at a grade between 0.3g/t to 0.7g/t gold and 0.1% to 0.3% copper for contained metal of between 10Moz and 27Moz gold and 1.0 to 3.7Mt copper (see ASX release dated 22 October 2024). The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource for the target area reported. It is uncertain if further exploration will result in the estimation of a Mineral Resource. * The gold equivalent calculation formula is AuEq (g/t) = ((Au grade x Au price x Au recov / 31.1035) + (Ag grade x Ag price x Ag recov / 31.1035) + (Cu grade x Cu price x Cu recov / 100)) / (Au price x Au recov / 31.1035). The prices applied were US$1,800/oz gold, US$4.50/lb copper and US$22/oz silver. Recoveries are estimated at 90% for gold, 78% for copper (excluded for oxide material), and 60% for silver based on metallurgical studies. In Sunstone’s opinion all the elements included in the metal equivalents calculation have reasonable potential to be recovered and sold. 27 ASX:STM JORC Classification Tonnage Mt Average Grade Material Content AuEq (g/t) Au (g/t) Ag (g/t) Cu (ppm) Cu (%) AuEq (Koz) Au (Koz) Ag (Koz) Cu (Kt) Indicated 5 0.63 0.42 0.81 1,456 0.15 100 100 100 7 Inferred 59 0.59 0.40 0.65 1,290 0.13 1,100 700 1,200 70 TOTAL 64 0.60 0.41 0.66 1,301 0.13 1,200 800 1,300 80 Resource Overview
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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 Institute of Geoscientists (AIG). Mr Rob Spiers has sufficient experience relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2012 Edition of the Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC Code). Mr Spiers holds 0.016% of the ordinary shares on issue of Sunstone Metals, and this shareholding does not constitute a substantial holding in the Company, nor does it impair Mr Spiers’s ability to provide an objective and unbiased assessment. The shareholding is disclosed in accordance with the JORC code transparency provisions. Mr Rob Spiers consents to the disclosure of the information in this report in the form and context in which it appears. Competent Persons Statement – El Palmar 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 Institute of Geoscientists (AIG). Mr Rob Spiers has sufficient experience relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2012 Edition of the Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC Code). Mr Rob Spiers consents to the disclosure of the information in this report in the form and context in which it appears. Exploration Results & Exploration Target Competent Person – Bramaderos and El Palmar The information in this report that relates to exploration results and exploration targets and results is based upon information reviewed by Dr. Bruce Rohrlach who is a member of the Australasian Institute of Mining and Metallurgy. Dr. Rohrlach is a full-time employee of Sunstone Metals Ltd and has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2012 Edition of the “Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves”. Dr. Rohrlach consents to the inclusion in the report of the matters based on his information in the form and context in which it appears. 28 See ASX announcements 3 Sept 2026 – Drilling expands Melonal porphyry system 3 Sept 2026 – Metallurgical tests deliver increased Bramaderos recoveries 18 August 2026 – Drilling returns 176m gold-copper intersection 3 August 2026 – Large gold-copper mineralization outside Bramaderos resource 2 July 2026 – Bramaderos poised for resource growth with recent drilling 2 June 2026 – Porotillo drilling intersects wide intervals of gold-copper 21 May 2026 – Drilling continues to intersect mineralisation 14 May 2026 – Drilling returns more large intersections at Bramaderos 11 May 2026 – Retraction announcement of scoping study 4 May 2026 – Drilling continues to extend Bramaderos mineralisation 21 April 2026 – Bramaderos Gold-Copper Project Scoping Study 14 April 2026, 4 May 2026, 21 May 2026 – Copete-Porotillo drilling results 23 February 2026 – Drilling underway to grow the 3Moz Bramaderos resource 4 February 2026 – Discovery of high grade surface mineralization at Porotillo 24 November 2025 – Bramaderos 2025 MRE and Exploration Target 22 October 2024 – El Palmar MRE and Exploration Target 21 August 2024 - More Limon high grade gold and silver in drilling 6 August 2024 - High-grade results expand size of Limon 17 July 2024 - El Palmar trenching enhances significant Resource potential 6 June 2024 - Limon drilling to start in known high-grade areas Limon ASX announcements (continued) 22 May 2024 - Visible gold in trenches 15 May 2024 - El Palmar significant gold-copper mineralisation at surface 18 April 2024 - Limon large mineralised system, multiple high-grade clusters 5 February 2024 – Limon Exploration Target – Additional JORC Information 31 January 2024 - Limon gold-silver discovery grows 19 December 2023 – Limon gold-silver discovery grows significantly 23 November 2023 – El Palmar gold target, Verde Chico work commencing 9 November 2023 – Large Limon Exploration Target 18 October 2023 – Limon – Bumper results, greatly expands scale 12 October 2023 – Limon drilling growing scale 18 September 2023 – High grade, near surface gold at Limon 11 September 2023 - El Palmar 2nd hole confirms T3 strongly mineralised porphyry 15 August 2023 - Limon gold discovery continues to grow 3 July 2023 – High grade gold and silver at Limon, Bramaderos 20 June 2023 – El Palmar T3 gold-copper porphyry discovery 28 April 2023 – El Palmar drilling intersects porphyry copper system 14 April 2023 – Limon emerging as major discovery with visible gold in hole 29 March 2023 – Limon epithermal drilling results 18 January 2023 – Limon delivers porphyry discovery 13 December 2022 – Bramaderos MRE and Exploration Target ASX:STM Competent Person Statement
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Bramaderos The Bramaderos porphyry Exploration Target within the Bramaderos concession is estimated from 5 areas – the extensions to the Brama-Alba system that are not captured in the Mineral Resource estimate (MRE), mineralisation drilled at the targets of Melonal and Limon porphyry mineralisation, and surface sampling and historical drilling at Copete and Porotillo. The Exploration Target does not include known porphyry mineralisation at Sandia, Playas, or Yeso. It was decided to not include these areas because Sunstone has not yet completed any or sufficient drilling in these areas. Further work in these areas will be undertaken and they are expected to contribute to an expanded Exploration Target in future. Several areas of mineralisation have been identified outside of the area of the MRE. The MRE captured all material within a ‘Mineralisation Wireframe’, and within an economically modelled pit. Some drill holes that intersected mineralisation are outside the mineralisation wireframe, and either within or outside the pit. Inadequate drilling exists in these areas to show continuity. Furthermore, the effect of the reasonable prospects of economic extraction was to exclude 14% of material. This material has been captured in the Exploration Target. Six domains were identified as having clear potential for additional mineralisation and these were reviewed either on a depth slice basis, or a block basis. Volumes were calculated and grade was assigned based on nearby data and on comparison with the overall Brama-Alba grade. The Melonal target is a continuation of the Brama-Alba system. It is geologically grouped with Brama-Alba. Recent drilling by Sunstone, and historical drilling from 2007, has confirmed that the Melonal target is mineralised, and that mineralisation is hosted in rocks the same as those drilled at the nearby Brama-Alba deposit. The mineralised rocks are coincident with a discrete sub-vertical magnetic anomaly measuring up to 400m in diameter, and with a vertical extent of over 1,000m. The Exploration Target for Melonal was considered to a depth of 500m. The Melonal target straddles the approved Bramaderos-01 and Bramaderos-02 concessions. Both the Copete and Porotillo porphyry systems lie within a single large and enveloping gold-in-soil geochemical anomaly greater than 0.2 g/t gold and greeater than 350 ppm Cu. At Copete on the northeast side of the soil geochemical anomaly, there are two syn-mineral intrusions at surface that exhibit strong quartz stockwork mineralisation within the intrusions and with weaker stockworks in the surrounding host rock. These intrusions cover an area of up to approximately 270m by 240m and exhibit silicic- argillic, argillic and minor advanced argillic alteration from the lower parts of a lithocap that overprint remnant potassic alteration. Trench ML-01 across the central part of these outcropping mineralised intrusions yielded 214m @ 0.50 g/t AuEq (ASX announcement 12 November 2024) whilst channel sample from ravines QC-02A and QC-03 yielded 63.7m @ 0.44 g/t AuEq and 60.20m @ 0.44 g/t AuEq respectively. The mapped mineralised intrusions are open to the southwest where they plunge under shallow alluvial cover of a narrow valley floor that runs between Copete and Porotillo. At Porotillo within the main body of the gold-in-soil geochemical anomaly, an extensive early-mineral quartz diorite intrusion hosts overprinting porphyry-related, disseminated and vein stockwork mineralisation over an area spanning up to approximately 530m by 310m. 29 ASX:STM On the basis of the extensive surface and sub-surface geochemical datasets at Porotillo and Copete, two domains were identified where there is coherent and elevated mineralisation defined in soil samples, rockchip samples, channel and trench samples, and in historical drilling. The first mineralised domain for which an exploration target has been defined (“Copete-Porotillo”) is approximately 700m long by approximately 200m wide, trends northeast and spans the Porotillo and Copete prospects. This domain contains sheeted porphyry-related quartz veins at both the Copete and Porotillo ends of the domain, which strike northeast-southwest parallel to the mineralised domain, which reinforces its geometry. The surface area of this domain was calculated in QGIS to be 129,745m2. The zone has been tested in three historic drill holes down to vertical depths of 140m, 370m and 530m in historical holes CURI05, EGCU005 and EGCU006. The target tonnage for this domain was based on the surface area footprint of mineralisation, a depth of 400m and a rock density of 2.7 g/cc, with estimated tonnage centered within the quoted range of 120 to 160 Mt. The assigned grade range of 0.40 g/t AuEq to 0.60 g/t AuEq was selected to span the calculated average grade (0.46 g/t AuEq) of the series of 10 bulk intersections encountered in six historical drill holes, a surface trench and three surface ravines which averaged 0.46 g/t AuEq. The upper end of the grade range was selected to account for evidence of significant areas at surface at Porotillo where grade in surface samples range from 0.71 g/t Au to 6.64 g/t Au. The second mineralised domain for which an exploration target has been identified (“Porotillo”) is an ovoid domain of up to approximately 255m by 170m in dimension that lies on the northwest side of the main Porotillo gold-in-soil anomaly. This domain is hosted in an early mineral quartz diorite intrusion locally transected by a mapped syn-mineral quartz diorite dyke and associated intrusion breccia. The surface area of this domain was calculated in QGIS to be 36,830m2. The zone has been tested in two historic drill holes, down to vertical depths of 185m and 135m, in EGCU008 and EGCU009, respectively. The target tonnage for this domain was based on the surface area footprint of mineralisation, a depth of 200m and a rock density of 2.7 g/cc, with estimated tonnage located at the upper end of the quoted range of 15 to 20 Mt. The assigned grade range of 0.36 g/t AuEq to 0.60 g/t AuEq was selected to span the calculated average grade (0.38 g/t AuEq) of the 2 bulk intersections encountered in historical drill holes EGCU008 and EGCU009. The upper end of the grade range was selected to account for evidence of significant areas at the surface, based on the eleven surface rockchip samples within the domain footprint, which averaged 0.54 g/t Au. Sunstone has drilled 8 effective diamond holes at the Limon porphyry target. Mineralisation has been intersected in a number of holes. A trench (LM_TR_01) was completed at Limon prior to drilling in an area of outcropping stockwork veining and minor secondary copper mineralisation. It returned 97m at 0.73g/t gold and 0.23% copper. A recent hole drilled under the trench has intersected similar stockwork veined intrusive and contains chalcopyrite. This area around Trench TR_LM_01 has been included in the porphyry Exploration Target where more drilling is required to allow inclusion in a Mineral Resource estimate. This target area will be further explored with drilling programs to be executed over the next two years, subject to the Company’s funding ability. Information on Exploration Targets
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30 ASX:STM Limon epithermal The Limon epithermal Exploration Target was estimated on target prospects where there was a combination of diamond drilling (by Sunstone), geological mapping, trenching, geochemistry (soils) and to a lesser extent geophysical data (magnetics) which could support the geological and mineralisation concept model. The Limon alteration area has been covered with soil sampling on a 50m x 50m grid. This survey is an important exploration method which identified several gold-in soil anomalies that are primary targets for drilling. The soil geochemical data is further interpreted using related element associations typical of epithermal systems, such as areas of somewhat coincident gold, silver, zinc, lead, copper, tellurium and arsenic. Target areas have also been strengthened using alteration mineralogy from a hand-held Terraspec instrument. These data assist in mapping the alteration zones most likely to be associated with epithermal mineralisation. Drilling at Limon has also intersected a high sulphidation system in holes LMDD004 and 006, which included intersections of 13.3m at 0.43% copper and 0.11g/t gold, within 59.6m at 0.16% copper. Standard geological mapping and rock chip sampling has also been undertaken across the Limon target area. The volume ranges for the initial Exploration Target in the Central Shoot were estimated using cross sections and 3-D modelling in Leapfrog software, based upon an analysis of drilling, mineralised rock types, grade distribution, potential for extrapolation of mineralisation continuity and interpreted geological risk. The volume ranges for the other components were estimated from geological interpretation and guided by extent of surface geochemical anomalism, supplemented by preliminary drilling. A conservative approach was taken to the potential distribution of gold and silver bearing veins. This target area will be further explored with drilling programs to be executed over the next two years, subject to the Company’s funding ability. Information on Exploration Targets (continued) El Palmar The Exploration Target within the El Palmar concession is estimated from within the T1, T2 and T3 areas. The Exploration Target does not include interpreted or known porphyry mineralisation at the T4 and T5 target areas. It was decided to not include these areas because Sunstone has not yet completed any drilling at T4 and has conducted only minor drilling at T5. Further work in these areas will be undertaken and they are expected to contribute to an expanded Exploration Target in future. The components of the exploration target are based on a combination of diamond drilling conducted by Codelco (during 2012) and by Sunstone (during 2022 and 2023), ground magnetics, multi-element soil sampling, multi- element rock chip and channel sampling, mulit-element trench sampling and deep magnetic inversion anomalies modelled from ground magnetic data. Wireframes of the areas within the Exploration Target areas were created in Leapfrog software using data interpreted from the Mineral Resource block model, iso-surface contours of modelled magnetic intensities, and grade ranges in available diamond drill holes. The volumes were multiplied by a specific gravity of 2.72g/cc (the average density of the T1 resource) to determine the tonnage range of the target. Grade ranges were determined with reference to drill intersection and surface rock chip assays. The next step in testing these targets is primarily diamond drill testing. The targets have been adequately defined, but drill programs still require detailed planning regarding the number of drill holes, their azimuths, dips, and final depths. Drilling of these targets will be undertaken over the next two years, subject to the company's funding availability.
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31 ASX:STM * Share price at close of trading 7 September 2026 Peer Comparison Data (page 22) ASX Ticker Company Name Share price ($/share)* Ordinay Fully Paid Shares on issue (M) Date of Appendix 2A Market Cap ($M) Net Debt Enterprise Value Mineral Resource Moz AuEq EV/ Oz AUEq Comments STM Sunstone Metals 0.200 284 23-Jul-26 57 (12) 45 4.8 9 Net Debt Source: 30 June 2026 Quarterly cashflow report TSO Tesoro Gold 0.990 180 17-Jul-26 178 (15) 163 1.8 89 Net Debt Source: 30 June 2026 Quarterly cashflow report CEL Challenger Gold 1.910 161 06-Aug-26 307 2 308 9.4 33 Net Debt Source: 30 June 2026 Quarterly cashflow report; Colorado V Mineral Resource at CEL's 50% share TTM Titan Minerals 0.605 288 20-May-26 174 (6) 168 4.4 38 Net Debt Source: 30 June Quarterly cashflow report; USD amounts translated at 0.70 STK Strickland Metals 0.075 2,640 27-Jul-26 198 (59) 139 9.3 15 Net Debt Source: 30 June 2026 Quarterly cashflow report STN Saturn Metals 0.555 664 28-Aug-26 369 (40) 328 2.8 116 Net Debt Source: 30 June 2026 Annual Report Tonnes Grade Grade Grade Grade Ounces Tonnes Grade Grade Grade Grade Ounces Tonnes Grade Grade Grade Grade Ounces Tonnes Grade Grade Grade Grade Ounces Ticker Company Name Mt g/t Au g/t Ag Cu % AuEq AuEq Mt g/t Au g/t Ag Cu % AuEq AuEq Mt g/t Au g/t Ag Cu % AuEq AuEq Mt g/t Au g/t Ag Cu % Eq AuEq STM Sunstone Metals - - - - - - 45 0.4 1.2 - 0.6 0.7 249 0.3 1.0 - 0.5 4.1 284 0.3 1.0 - 0.5 4.8 TSO Tesoro Gold 2 1.2 - - 1.2 0.1 38 1.1 - - 1.1 1.4 11 1.0 - - 1.0 0.4 52 1.1 - - 1.1 1.8 CEL Challenger Gold - - - - - - 76 0.8 4.2 0.0 0.9 2.2 415 0.4 2.4 0.1 0.5 7.2 598 0.4 2.2 0.1 0.5 9.4 TTM Titan Minerals - - - - - - 17 2.2 13.9 - 2.4 1.4 48 1.7 11.8 - 2.0 3.0 66 1.8 12.4 - 2.1 4.4 STK Strickland Metals - - - - - - 30 0.8 7.2 0.1 1.3 1.3 187 0.9 4.9 0.1 1.3 8.0 217 0.9 5.3 0.1 1.3 9.3 STN Saturn Metals 5 0.6 - - 0.6 0.1 129 0.5 - - 0.5 2.1 40 0.5 - - 0.5 0.6 174 0.5 - - 0.5 2.8 Total Mineral ResourcesMeasured Indicated Inferred ASX Ticker Company Name Au Ag Cu TSO Tesoro Gold Pre-development 95% n/a n/a CEL Challenger Gold Pre-development 85-95% 60-90% 85% TTM Titan Minerals Pre-development 93% 70% n/a STK Strickland Metals Pre-development 80% 80% 80% STN Saturn Metals Pre-development n/a n/a n/a ASX Announcement, 27 August 2026 31 December 2025 Annual Report Gold equivalent ounces and grade are calculated using United States dollar pricing for Gold ($2,000/oz.), Copper ($9,500/t), Silver ($50.00/oz.) and Molybdenum ($20,000/t), and metallurgical recoveries for each metal on a site by site basis, as [(metal grade x metal price x metal recovery) / (gold price x gold recovery)] from the respective Resource and Reserve statements. Mineral Resource Source Gold equivalent formula Recovery percentages 31 December 2025 Annual Report ASX Announcement, 15 July 2026 30 June 2026 Annual Report Stage of project