Sunstone Metals Lifts Bramaderos Resource 72% to 6.2Moz AuEq
Key Takeaways
- Bramaderos' resource jumped 72%, or 2.6Moz, to 6.2Moz AuEq (464Mt at 0.42g/t), up from 3.6Moz in November 2025.
- Indicated ounces climbed 450% to 3.3Moz AuEq, which Sunstone says is available for conversion to Ore Reserves.
- Not all of the growth is drilling: a deeper pit shell, higher price assumptions and better gold recoveries also contributed, and average grade fell from 0.50g/t to 0.42g/t.
- An updated Exploration Target of 4.4-11.2Moz AuEq sits on top of the resource, though it is conceptual and below the prior 5.0-12.9Moz.
- Sunstone is evaluating a new Scoping Study but has not committed to one, and Limon and Copete-Porotillo drilling over one to two years depends on funding.
Bramaderos resource jumps 72% to 6.2Moz AuEq
The Sunstone Metals (ASX: STM) Bramaderos Mineral Resource Estimate (MRE) has risen by 72%, or 2.6Moz AuEq, to 6.2Moz AuEq (464Mt at 0.42g/t AuEq), according to its 13 October 2026 announcement. The update follows the company’s 2026 drill program at the Bramaderos Gold-Copper Project in southern Ecuador.
The previous estimate, from November 2025, stood at 220Mt at 0.50g/t AuEq for 3.6Moz AuEq. AuEq means gold-equivalent, a single figure that combines gold, copper and silver.
Sunstone names three drivers behind the increase:
- Additional drilling and trenching at Melonal, adding 0.3Moz AuEq
- A new MRE for Copete and Porotillo, adding 1.3Moz AuEq
- A deeper and larger pit shell used for reporting, due to the additional Melonal drilling and trenching, an increase in pricing assumptions, and improved metallurgical recoveries for gold
That third driver matters. Not all of the growth comes from drilling alone, so the larger pit shell and updated assumptions also carry weight.
Patrick Duffy, Managing Director
“This MRE update is a significant milestone in the progression of Bramaderos towards being a large gold-copper development…”
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Indicated Resource up 450% to 3.3Moz AuEq
For investors, the Indicated category is the one to watch. The Indicated Resource now totals 229Mt at 0.45g/t AuEq for 3.3Moz, which Sunstone says is available for conversion to Ore Reserves.
The company says this establishes a strong foundation for future studies of an open pit mine, which it characterises as having early higher-grade ore and a very low stripping ratio. Those are Sunstone’s descriptions, not independent findings.
The 450% increase applies to Indicated ounces only. The 72% increase refers to total contained AuEq.
| Classification | Tonnes (Mt) | AuEq (g/t) | AuEq (koz) | Cu (kt) |
|---|---|---|---|---|
| Indicated | **229** | **0.45** | **3,300** | **240** |
| Inferred | **236** | **0.38** | **2,900** | **230** |
| Total | **464** | **0.42** | **6,200** | **470** |
Figures may not sum due to rounding. The second table compares the 2025 and 2026 estimates.
| MRE | Classification | Tonnes (Mt) | AuEq (g/t) | AuEq (koz) |
|---|---|---|---|---|
| 2026 | Indicated | **229** | **0.45** | **3,300** |
| 2026 | Inferred | **236** | **0.38** | **2,900** |
| 2026 | Total | **464** | **0.42** | **6,200** |
| 2025 | Indicated | **40** | **0.56** | **600** |
| 2025 | Inferred | **190** | **0.49** | **2,900** |
| 2025 | Total | **220** | **0.50** | **3,600** |
Average grade fell as tonnage expanded, from 0.50g/t to 0.42g/t AuEq overall. The source notes that AuEq differences between the two estimates include variations in the calculation.
Key supporting facts:
- The estimate is based on 91 drill holes totalling 36,855m
- Independent consulting firm Exora Consulting Pty Ltd prepared the MRE
- It is reported under the JORC Code (2012 Edition)
- It uses a 0.3g/t AuEq cut-off within an optimised pit shell
What AuEq and resource classification mean for investors
AuEq converts copper and silver into the gold ounces they would equal, so a polymetallic deposit can be compared on one scale. Sunstone used prices of US$3,000/oz gold, US$6.0/lb copper and US$40/oz silver, with overall recoveries of 91% gold, 78% copper and 60% silver.
Classification reflects confidence. Indicated Resources have a reasonable level of confidence in geological and grade continuity, while Inferred Resources carry lower confidence. A bigger Indicated share therefore means a larger portion of the estimate rests on firmer ground.
Higher price assumptions contribute to the increase, so the figures are sensitive to those prices. Porotillo transition material uses more conservative recoveries of 65% copper and 76% gold, with metallurgical testwork ongoing.
Exploration Target of 4.4Moz – 11.2Moz AuEq signals further upside
Sunstone also reported an updated Exploration Target of 300-474Mt at 0.46-0.74g/t AuEq for 4.4-11.2Moz AuEq, which is additional to the October 2026 MRE. The headline bullets round this to “4Moz – 11Moz”.
| Target | Tonnage (Mt) | AuEq grade (g/t) | AuEq (Moz) |
|---|---|---|---|
| Porphyry sub-total | **270-430** | **0.41-0.69** | **3.5-9.5** |
| Limon (Epithermal) | **30-44** | **0.9-1.2** | **0.9-1.7** |
| Total Bramaderos | **300-474** | **0.46-0.74** | **4.4-11.2** |
The announcement contains some inconsistencies. The headline bullet gives Limon as 30-40Mt, while the body and Table 3 say 30-44Mt. The “About Sunstone” section cites 3.5-8.5Moz for porphyry and 6.3Moz/474Mt, which conflict with the body. This article uses the body and Table 3 figures.
The November 2025 combined target was 5.0-12.9Moz AuEq. The new target is lower because material converted to resource was removed, partly offset by further target potential identified through exploration and review.
Sunstone describes a cluster of porphyry systems across 2km by 2km. Hole MEDD005, between Melonal and Alba, intersected 9.4m at 17.23g/t AuEq.
The potential quantity and grade of the Exploration Targets is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource, and it is uncertain whether further exploration will result in one.
The target is estimated from five areas:
- Updated Porphyry Exploration Target at Brama-Alba
- Updated Porphyry Exploration Target at Melonal
- Updated Porphyry Exploration Target at Copete-Porotillo
- Porphyry Exploration Target at Limon (limited to the upper section from surface)
- Limon Epithermal Exploration Target
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Next steps for Bramaderos
Sunstone’s immediate priorities are to continue resource growth between Melonal and Copete and south of Porotillo, target high-grade potential between Melonal and Alba, and keep testing deeper porphyry potential at Limon and the Limon epithermal systems. Drilling will also aim to convert Inferred Resources to Indicated.
Sunstone is evaluating the potential for a new Scoping Study. The announcement does not say one is committed. Drilling programs for the Limon and Copete-Porotillo target areas are to be executed over the next one to two years, subject to the Company’s funding ability.
The case rests on scale, near-surface open-pit potential and further growth. The next milestones are the drilling results and any decision on a new Scoping Study.
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