Tesoro Gold Lifts 1.47Moz to Measured and Indicated Setting Up Maiden Ore Reserve
Key Takeaways
- 1.47Moz of Ternera's gold — 78% of the total resource — has been reclassified into Measured and Indicated categories, a 348koz increase in high-confidence ounces compared to the August 2025 estimate.
- Tesoro has defined a Measured resource of 95koz for the first time, representing the highest confidence category under the JORC Code and the tightest possible geological certainty.
- The total constrained Mineral Resource Estimate stands at 51.6Mt at 1.10g/t Au for 1.82Moz, underpinned by 153,180 metres of diamond drilling across 474 holes.
- The maiden Ore Reserve is targeted for September 2026, with the Definitive Feasibility Study expected by end of CY2026 — two development milestones in the same calendar year.
- Assay results from four recently completed near-deposit holes are expected in coming weeks, with extensional and new-discovery drilling continuing across a 40km-plus mineralised corridor at El Zorro.
Ternera resource confidence lifts as 1.47Moz moves into Measured and Indicated
Tesoro Gold has delivered an updated Mineral Resource Estimate for its Ternera Gold Deposit at the El Zorro Gold Project in Chile, with 1.47Moz (78% of contained gold) now classified as Measured and Indicated. The upgrade reflects a 348koz increase in higher-confidence M&I ounces compared to the August 2025 estimate, and establishes the foundation for a maiden Ore Reserve expected September 2026. The total constrained MRE stands at 51.6Mt at 1.10g/t Au for 1.82Moz (0.30g/t cut-off, US$3,500/oz pit shell). Critically, Tesoro has defined a Measured resource of 95koz for the first time, representing the highest confidence category under the JORC Code. The unconstrained global MRE now sits at 1.93Moz at 1.07g/t Au.
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Breaking down the upgraded resource
What changed here is classification confidence, not headline ounces. The total constrained resource remains stable at 1.82Moz, but the proportion sitting in Measured and Indicated categories jumped materially. Indicated ounces increased by 252koz (44%), while the 95koz Measured component appears for the first time. Total M&I now stands at 1.47Moz at 1.14g/t Au. The reclassification was underpinned by 27,000m of infill drilling completed this year, bringing total diamond drilling across Ternera to 153,180m from 474 holes. The classification split now reads: Measured 5%, Indicated 73%, Inferred 22%.
| Classification | Tonnes (Mt) | Grade (g/t Au) | Gold (koz) | Share of Resource |
|---|---|---|---|---|
| Measured | 2.4 | 1.24 | 95 | 5% |
| Indicated | 37.9 | 1.13 | 1,371 | 73% |
| Inferred | 11.3 | 0.98 | 356 | 20% |
| Total | 51.6 | 1.10 | 1,822 | 100% |
Why Measured and Indicated ounces matter
JORC resource classifications exist to tell you how confident the geologists are in the continuity and grade of the mineralisation. Inferred resources sit in areas where drill spacing is typically less than 50m — enough to suggest mineralisation exists, but not enough to define it with precision. Indicated resources tighten that spacing to typically less than 25m, giving you higher confidence in both grade and geometry. Measured resources are the tightest category, with drill spacing typically less than 12.5m — the geology is known with the highest degree of certainty.
What this means for you as an investor is straightforward. Only Measured and Indicated resources can convert into an Ore Reserve. An Ore Reserve is the mineable, economically-defined portion of a deposit — it incorporates modifying factors like mining dilution, recovery, processing costs, and geotechnical constraints. Inferred resources cannot support an Ore Reserve calculation under the JORC Code. The shift from 1.12Moz M&I (August 2025) to 1.47Moz M&I (current) materially de-risks Ternera’s path toward development. The resource base now has the confidence level required to underpin mine planning, financing, and permitting decisions.
Building toward a maiden Ore Reserve and DFS
The upgraded M&I base directly supports the maiden Ore Reserve calculation, which is expected September 2026. An Ore Reserve incorporates modifying factors developed through technical, engineering, and economic studies — mining method, dilution, recovery, metallurgical performance, processing costs, capital requirements, pit slope angles, and economic cut-off grades. Tesoro has stated the Ore Reserve work is well advanced.
The maiden Ore Reserve will feed into DFS-level mine planning, with the Definitive Feasibility Study targeted by the end of CY2026. The DFS will establish capital and operating cost estimates, production schedules, infrastructure requirements, and project economics at a bankable level of detail. The current resource update positions Tesoro to move through these studies with a materially higher-confidence geological foundation than existed six months ago.
Zeff Reeves, Managing Director
“This updated MRE is a significant upgrade for the Ternera Gold Deposit supported by the 27,000m of drilling completed this year. Ternera now contains 1.47Moz of gold in the higher-confidence Measured and Indicated categories, representing 78% of the total Mineral Resource. Since discovery, more than 160km of diamond drilling has systematically defined a substantial, high-confidence gold resource. This work provides the foundation for Ternera’s maiden Ore Reserve, which is well advanced, and supports the broader technical studies required for project development.”
Positioned in a premier mining jurisdiction
El Zorro is located in Chile’s Atacama Region, 900km north of Santiago. Ternera sits 13km inland from the Pacific Ocean, 57km by road from the port town of Caldera. The deposit benefits from low-altitude coastal setting, sealed road access, grid power, and water. Chile is positioned as a well-established, mining-friendly jurisdiction with a regulatory framework that supports responsible mine development. Tesoro’s 95%-owned Chilean subsidiary owns 94.5% of El Zorro (fully diluting JV structure), providing operational control and the majority of economic exposure.
A pipeline of near-term catalysts
Tesoro has flagged multiple potential value triggers over the coming months. Ternera remains open in multiple directions, with drilling continuing at extensional targets. Assay results from four recently completed near-deposit holes are expected in the coming weeks. The broader El Zorro District contains high-priority exploration targets across a 40km-plus mineralised corridor, with new-discovery drilling underway.
Key upcoming milestones include:
- Maiden Ore Reserve for Ternera (September 2026)
- El Zorro development-readiness and DFS update
- Assay results from four recently completed near-deposit holes (expected in coming weeks)
- Refined regional exploration plan across the 40km-plus mineralised corridor
- New-discovery drilling across high-priority El Zorro District targets
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The investment case
Tesoro is transitioning from explorer to developer. The confidence uplift at Ternera de-risks the flagship asset by establishing a materially higher M&I resource base to support Ore Reserve conversion and DFS-level mine planning. The September 2026 maiden Ore Reserve and end-CY2026 DFS delivery are the critical near-term milestones. Meanwhile, exploration upside remains across the broader El Zorro District, with multiple targets under active drilling and a 40km-plus mineralised corridor still being refined. The current resource update positions Tesoro with both development momentum at Ternera and discovery optionality across the district.
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