- 01Ternera: 1.28 Moz from 42.8 Mt @0.93 g/t
- 02Open pit only; >13-year life at 3 Mtpa
- 03DFS targeted 2026; capex US$276.5m
- 04PFS: NPV US$994m, IRR 57%, payback 17 months
Tesoro Gold (ASX: TSO) has established a maiden Ore Reserve of 42.8 million tonnes at 0.93 grams per tonne gold for 1.28 million ounces at its Ternera deposit in Chile.
Contained entirely within a single open pit, the reserve represents about 87% of the 1.47Moz of gold contained in the Measured and Indicated components of the August 2026 mineral resource estimate.
It supports a project production life of more than 13 years at a planned processing rate of 3.0Mtpa, with an average grade of 1.16g/t over the first 10 years of production.
The maiden reserve provides the development base for Tesoro’s El Zorro gold project as the company advances a definitive feasibility study targeted for completion during calendar 2026.
Optimised Shell Selected
The Ore Reserve comprises 2.8Mt of Proved Reserves at 1.05g/t for 93,000 ounces and 40.1Mt of Probable Reserves at 0.92g/t for 1.19Moz.
No Inferred Mineral Resources are included, with the reserve derived solely from Measured and Indicated material in the August 2026 MRE.
The reserve pit is based on a shell selected from optimisation using a US$3,000 per ounce gold price, while the mine schedule assumes conventional open-pit mining and a 3.0Mtpa processing operation.
“The Ternera gold deposit represents a rare, single open-pit development opportunity in a world-class mining friendly country,” managing director Zeff Reeves said.
“We will continue advancing the technical and development workstreams for El Zorro in parallel with drilling as multiple rigs pursue extensions to the existing Ternera resource and high-priority discovery targets across the broader district."
CIP Processing Flowsheet
Three phases of metallurgical test work have supported a conventional crushing, grinding, gravity, and carbon-in-pulp (CIP) processing flowsheet for the project.
Testing across representative material returned overall gold extractions between 92.4% and 97.4%, with the selected 125 micrometre grind size delivering 48-hour recoveries of about 95.1% to 96.0%.
Tesoro has adopted a design gold recovery of 94.5% for the Ore Reserve calculation, with test work also identifying no deleterious elements or preg-robbing tendencies.
Planned infrastructure includes a processing plant, waste rock dumps, run-of-mine pads, workshops, and water and power facilities, with grid connection and process-water options also under consideration.
PFS Economics
Pre-production capital has been estimated at US$276.5 million at pre-feasibility study level, with operating costs estimated at US$1,538 per ounce of gold produced.
Using a US$3,500/oz gold price for the PFS-level financial evaluation, Tesoro reported a post-tax net present value of US$994m, a post-tax internal rate of return of 57%, and a 17-month payback period.
Environmental and sectorial permit applications are about 75% complete, with the full environmental impact assessment, sectorial permits and closure plan targeted for submission in the first quarter of 2027.
Mr Reeves said that the 87% gold classified within the Measured and Indicated categories “is a strong conversion outcome reflective of the consistency of mineralisation at Ternera”.
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