Orosur Mining (AIM:OMI) said it will move its APTA prospect in Colombia into a formal resource drill-out program, after deciding the gold deposit now holds enough data to support efforts towards defining a mineral resource estimate.
The TSX Venture and AIM-listed gold explorer, which runs three rigs across its wholly owned Anzá project in the Mid-Cauca gold belt, reported the latest assays from APTA on Wednesday: hole MAP109 returned 15.35m at 0.97g/t gold, while MAP110 returned 43.55m at 1.53g/t gold, including a higher-grade section of 14.2m at 3.1g/t gold.
Orosur called both results "moderate" but said they add to the geological understanding of APTA, which has now seen more than 40,000m of drilling since 2012 without a declared resource.
Once the current hole, MAP111, is finished, the company will temporarily suspend drilling at APTA and move that rig to Pepas, where new target areas have constrained access better suited to its portability.
Planning for the resource drill-out program and development of access tracks mean that work is likely to start early in the new year, targeting the highest-grade zones first alongside undrilled areas with the greatest mineralisation potential.
"Work at Anzá has ramped up in recent times, accelerating on multiple fronts," said chief executive Brad George, adding that a new government and mining administration in Colombia, together with a solid balance sheet, gave the company confidence to advance Pepas, move APTA toward a resource and explore the El Cedro/El Yarumo cluster in parallel.
At Pepas, where Orosur published a maiden mineral resource estimate in February, drilling east and northwest of the deposit has produced no significant results to the east, while holes to the northwest continue to outline a broad, lower-grade zone running between 0.3g/t and 0.7g/t gold.
The company is now shifting focus to a new target roughly 800m south of the Pepas deposit, where mapping and rock-chip sampling have returned multiple grams-per-tonne gold, and plans to begin drilling there within coming weeks using the rig freed up from APTA.
At El Cedro, the redrilled hole CED001A, restarted from surface after the original hole became unrecoverable at 267m, has progressed beyond that failure depth, with core recovery resuming at a downhole depth of 200m.
Should drilling continue successfully, Orosur intends to drill two further holes from the same pad, and is in discussions to mobilise a second rig to a separate pad at El Cedro targeting the intrusion's higher-level cupola and old artisanal workings grading up to 8g/t gold.
The company has also identified a new target, El Yarumo, roughly 2.4km northwest of El Cedro, where mapping has defined a 500m-by-500m zone of quartz-sulphide veins and hydrothermal breccias, with surface sampling returning more than 64 samples above 0.1g/t gold, including 20 above 1g/t gold and a maximum of 10.67g/t gold.
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Orosur said the vein textures at El Yarumo show geological similarities to the Marmato deposit roughly 120km south in the Mid-Cauca belt, and it is now planning access and permitting for drilling there, likely in the first quarter of 2027.
On permitting, Orosur has completed the final draft of the Programa de Trabajos y Obras for Pepas, and the plan of works is being submitted to Colombian authorities to begin the formal mining approval process.
The company's conceptual base case envisages mining 500 tonnes per day, or roughly 175,000 tonnes a year, blending Pepas material with surrounding lower-grade material outside the resource estimate for potential output of approximately 25,000 ounces a year over ten years.
Following Colombia's recent elections and the appointment of new mining ministry leadership in August, Orosur plans to present the PTO to the relevant authorities before commissioning a preliminary economic assessment compliant with NI 43-101, to run alongside the environmental and social permitting needed to underpin development at Pepas.