St Barbara Lifts 15-Mile Processing Hub Gold Resources 20% to 2.5 Moz

Substantial Resource Upgrade at 15-Mile Processing Hub

St Barbara Limited (ASX:SBM) has unveiled a 20% increase in its Mineral Resources Estimate for the 15-Mile Processing Hub Project in Nova Scotia, boosting contained gold by 0.5 million ounces to a total of 2.5 million ounces. The updated resource now stands at 62.4 million tonnes grading 1.2 grams per tonne gold, reflecting a significant step forward in the company’s Atlantic operations.

The upgrade stems from a comprehensive validation and incorporation of a substantial historical drilling dataset, including 436 drill holes totaling 71,000 metres that had not previously been factored into resource models. This historical data, primarily from the mid-to-late 1980s, was rigorously audited for quality and geological consistency, enabling St Barbara to transition from Multiple Indicator Kriging to Ordinary Kriging for resource estimation, an approach better suited to the denser, higher-confidence data.

Technical Refinements Drive Resource Growth

The resource increase is underpinned by updated geological interpretations and a revised estimation methodology. At the 15-Mile Mine, improved lode continuity and expanded optimised pit shells, notably at the Egerton-MacLean pit, have added materially to contained gold. Similarly, the Old Austen Mine shows enhanced down-dip continuity beyond current pit limits, while Old Mitchell Mine’s revised modelling yields a higher average grade despite a slight reduction in tonnage, maintaining overall contained gold.

Metallurgical test work supports the project’s economic potential, with average gold recoveries ranging from 90% to 97% across deposits using conventional crushing, grinding, gravity recovery, and carbon-in-leach processing. No significant deleterious elements have been identified, and environmental baseline studies report no material constraints, benefiting from existing infrastructure and permitting progress.

Next Steps in Project Development

St Barbara plans to update the Pre-Feasibility Study (PFS) for the 15-Mile Processing Hub by the end of Q1 Sep FY27, which will incorporate the revised resource estimate and enable an updated Ore Reserves calculation. The Feasibility Study incorporating this resource update is expected in Q4 Jun FY27. Meanwhile, new drill targets at the 15-Mile Mine have been identified and are under evaluation for a planned FY27 drilling campaign, potentially extending resource growth.

This resource enhancement complements St Barbara’s broader portfolio, lifting Group Mineral Resources to 5.4 million ounces, including 2.9 million ounces attributable at New Simberi. The timing follows recent operational milestones such as environmental approvals and investment decisions for the Touquoy Restart, highlighting continued momentum in the company’s Atlantic operations.