St Barbara Limited is accelerating exploration at its Old Austen Mine in Nova Scotia, with a specific focus on the underground mining potential lying below the planned open pit design. The company has prioritised assessment of the Old Austen Mine Down-Plunge Prospect and Mill Shaft West to drill test in late 2027 and early 2028. This represents a meaningful opportunity for resource growth, as the open pit design was intentionally constrained to minimise surface disturbance and protect waterway setbacks, leaving known mineralisation below the pit shell untested.
The updated geological model supporting the down-plunge drilling program is based on quality assurance work applied to St Barbara’s significant historical drilling dataset. Significant intercepts from historic drilling confirm the continuity of mineralisation at depth, with examples including 1.84 metres true width grading 163.7 g/t gold from 123.6 metres depth, 3.70 metres at 66.1 g/t gold from 298.4 metres, and a lower-grade intercept of 12.80 metres at 3.3 g/t gold from 524.2 metres. The mineralisation dips steeply to the north and is hosted within argillite and greywacke formations, with the geological model indicating the mineralisation remains open at depth.
This exploration program is integrated into St Barbara’s broader strategy for the 15-Mile Processing Hub Project, where an updated mineral resource estimate was announced in July 2026. By testing the down-plunge and along-strike potential that cannot be captured within the constrained open pit design, the company may unlock additional tonnes of mineralisation amenable to underground extraction. Underground mining of lower-grade, deeper mineralisation can be economically viable when processing facilities already exist, making this an attractive avenue for resource expansion.
The near-term work program includes a high-resolution UAV magnetic survey across 22 square kilometres surrounding the Old Austen Mine in early October, followed by comprehensive structural analysis in the second half of FY27. These surveys will refine drill targets ahead of the major drilling campaign planned for the Nova Scotia spring and summer of 2027. The phased approach lets St Barbara build confidence in the geological model before committing to an extensive drill program.
Investors should monitor the results of the UAV survey and structural review, as these will define the shape and scale of the drilling campaign to follow. Positive drill intersections down-plunge could represent material resource growth for the project. St Barbara has flagged this announcement as price sensitive under ASX continuous disclosure rules.
View the full ASX announcement (PDF)
About St Barbara Limited (ASX: SBM)
St Barbara Limited is an Australian-based gold mining company with operations in Canada and Papua New Guinea. The company operates the Atlantic Operations in Nova Scotia, Canada, which includes the Touquoy mine, and the Simberi Operations in the province of New Ireland, Papua New Guinea. The company engages in the exploration, development, mining, and sale of gold, with additional interest in silver exploration.
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