Sunstone Metals Unveils High-Grade Gold Discovery at Bramaderos Project

Sunstone Metals Expands Mineral Footprint at Bramaderos with Strong Surface Sampling Results

Recent channel sampling at Sunstone Metals' (ASX: STM) Bramaderos Project in southern Ecuador has delivered compelling results that highlight significant resource growth potential across multiple prospects.

Copete Porphyry System Shows Expanded Mineralisation Footprint

Sunstone Metals' latest surface sampling program has successfully expanded the known footprint of stockwork mineralisation at the Copete porphyry system, adding confidence to this emerging discovery within the Bramaderos project portfolio.

Channel sampling from five ravines surrounding the previously identified mineralised trench ML01 has returned substantial runs of porphyry mineralisation on both flanks of the central ridge. These results are particularly significant as they build upon the earlier trench result at Copete which delivered 214m @ 0.5 g/t AuEq including 113m @ 0.64 g/t AuEq.

The ravine mapping at Copete has identified:

• Two mineralised intrusions covering an area of 300m by >250m
• Strong stockwork-veining throughout the intrusions
• Porphyry stockwork veining extending into surrounding wall-rock intrusions
• Continuity of the central mineralised syn-mineral intrusions to the southwest

Notable intersections from the ravine sampling include:

• QC-2a: 63.7m @ 0.44 g/t AuEq
• QC-2b: 48.3m @ 0.35 g/t AuEq
• QC-3: 105.1m @ 0.22 g/t AuEq (including 40.8m @ 0.33 g/t AuEq)
• QC-4: 88.1m @ 0.19 g/t AuEq
• QC-5: 48.9m @ 0.19 g/t AuEq (including 12.4m @ 0.36 g/t AuEq)
• QC-6: 90.8m @ 0.24 g/t AuEq

"The latest results out of Copete are very promising and reveal a coherent zone of porphyry-related alteration and vein mineralisation that will enable exploratory holes to be sited to test the sub-surface core of this recently discovered outcropping porphyry system," said Sunstone Managing Director Patrick Duffy.

Brama Northeast Delivers High-Grade Gold Discovery

In a second area of focus, surface sampling along an access road off the northeast edge of the Brama porphyry deposit has uncovered a substantial zone of gold mineralisation across an epithermal corridor, including:

• A continuous channel sample yielding 142.3m @ 0.29 g/t AuEq
• A higher-grade sub-interval of 15.8m @ 0.68 g/t AuEq
• A separate rock chip sample containing fine epithermal veinlets that returned an exceptional 38.3 g/t Au

Importantly, this newly identified mineralised zone lies outside the current Brama-Alba resource but within the limits of the economic open pit as modelled in 2022, suggesting significant resource expansion potential. The company's high-grade gold discovery at Bramaderos continues to deliver impressive results, further enhancing the project's potential.

"The latest channel sampling in a second area of activity northeast of Brama has yielded a wide zone of gold mineralisation and with local high grades that are within the confines of the modelled open pit but outside the current resource. This provides high confidence that the Brama-Alba resource will continue to grow when we progress future resource expansion drilling," Duffy added.

Understanding Porphyry Gold-Copper Systems

Porphyry deposits are large, low-grade ore bodies that typically contain copper and gold mineralisation distributed throughout a large volume of rock. They represent some of the world's largest sources of copper and gold.

At Bramaderos, the porphyry systems are characterised by:

• Stockwork veining: Networks of small veinlets that form a mesh-like pattern throughout the rock
• Alteration zones: Different minerals form in concentric shells around the mineralised core
• Multiple intrusive phases: Different pulses of magma that introduce mineralisation

The stockwork veining seen at Sunstone Metals' new mineral discovery involves a network of small mineral-filled fractures that create a mesh or net-like pattern throughout the host rock. These veins typically contain quartz, sulphide minerals, and the economically valuable metals such as gold and copper.

Alteration zones in porphyry systems form as hot, mineral-rich fluids interact with the surrounding rock. These zones commonly progress outward from potassic alteration (containing minerals like biotite and potassium feldspar) at the core, through phyllic alteration (containing sericite and quartz), to argillic alteration (containing clay minerals) at the periphery.

The latest surface sampling results are particularly encouraging as they demonstrate mineralisation extending from known centres into surrounding areas, suggesting larger overall systems than previously delineated.

Strategic Path Forward for Sunstone Metals

Sunstone's exploration team is progressively exploring the northern margin of the Brama-Alba orebody with detailed geological mapping and selective surface sampling over gold-in-soil anomalies to refine areas for resource expansion.

In parallel, a team of in-house surveyors is undertaking detailed DGPS surveying of topography across the project, expanding the existing coverage to include contiguous blocks at Melonal and Copete where future resources are expected to be established.

These activities support Sunstone's broader strategy across its two Ecuadorian projects:

1. Bramaderos Project: Contains an initial Mineral Resource estimate of 156Mt at 0.53g/t AuEq for 2.7Moz AuEq, with a porphyry Exploration Target of between 3.3Moz and 8.6Moz AuEq and the Limon epithermal gold-silver Exploration Target of 0.9-1.7Moz AuEq.

2. El Palmar Project: Contains an initial Mineral Resource estimate of 64Mt at 0.60g/t AuEq for 1.2Moz AuEq, with a porphyry Exploration Target of between 15Moz and 45Moz AuEq.

Sunstone Metals' New Mineral Discovery: Gold in Epithermal Corridors

The high-grade gold sample (38.3 g/t Au) identified in the Brama Northeast area represents a potentially significant discovery for Sunstone Metals. This type of epithermal gold mineralisation typically forms at relatively shallow depths and lower temperatures compared to the deeper porphyry systems.

Epithermal gold deposits are characterised by:

• Vein structures: Narrow, high-grade structures that can contain bonanza gold grades
• Distinctive textures: Including banding, bladed textures and vugs (small cavities)
• Specific mineral assemblages: Including adularia, quartz, and clay minerals

These epithermal systems often develop above or adjacent to porphyry deposits, creating potential for multiple styles of mineralisation within a single district. At Bramaderos, the identification of this high-grade gold in epithermal veins alongside the broader porphyry mineralisation suggests a complex and potentially valuable mineral system.

Similarly, high-grade gold discovery potential at Woodlark and Sierra Nevada Gold's New Pass acquisition demonstrate the significant opportunities that exist in the precious metals space globally.

Investment Opportunity

Sunstone Metals presents a compelling investment case based on several key factors:

1. Multiple Gold-Copper Systems: The company controls multiple porphyry and epithermal systems with demonstrated mineralisation across its two Ecuadorian projects.

2. Significant Resource Growth Potential: The latest surface sampling results reinforce the potential for substantial resource expansion at Bramaderos.

3. Staged Development Strategy: The company is prioritising the Limon epithermal deposit as a potential near-surface high-grade gold-silver development opportunity before developing the much larger porphyry gold-copper-silver opportunities.

4. Experienced Team: Sunstone's team has been involved in significant discoveries of porphyry and epithermal copper-gold mineralisation at Tujuh Bukit in Indonesia and Cascabel in Ecuador, and the successful development of mining operations.

5. Corporate Development: The company is progressing "strategic corporate and asset discussions with several parties," suggesting potential partnership or transaction opportunities.

The continued success of Sunstone Metals' exploration programs at Bramaderos, particularly at Copete and Brama Northeast, demonstrates the company's ability to expand its resource base and move toward its goal of establishing multi-decade gold-copper mining centres in Ecuador. In addition to gold discoveries, companies exploring for rare earth elements and those with established assets like the Apollo Hill gold resource are also finding success in the current market. With each new sampling program, Sunstone Metals' new mineral discovery potential continues to grow, positioning the company as an emerging player in the Ecuadorian mining sector.

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