Broken Hill Mines reveals the scale of Rasp’s Centenary opportunity

Centenary target reaches 17.1Mt in high case

Broken Hill Mines Limited (ASX:BHM) has put numbers around the scale of its Centenary discovery, outlining a conceptual Exploration Target of 13.2Mt to 17.1Mt at the Rasp Mine in Broken Hill. The low case carries an estimated 8.4% zinc equivalent grade, while the high case reaches 12.5%, equivalent to between 1,109kt and 2,137kt of contained zinc equivalent.

The target is additional to Centenary’s existing inferred Mineral Resource of 4.8Mt at 9.2% zinc equivalent, containing 443kt of zinc equivalent. It is based solely on the newly interpreted Plimer A Lode, which the company says has been defined over a 1,600m strike and remains open, including more than 2,000m of untested strike to the north.

Drilling has reshaped the Centenary interpretation

The estimate follows 48 drill holes, combining historical drilling with work completed by previous operators and Broken Hill Mines. The company’s August Centenary drilling had already extended the interpreted strike to 1,600m and delivered thick, high-grade intercepts outside the existing resource.

Among the reported results are 25.8m at 11.7% zinc equivalent from WMDD6391, including 10.9m at 17.3%, and 17.8m at 10.1% from WMDD6400W1, including 5.4m at 19.5%. Another hole returned 6.4m at 23.1% zinc equivalent. These are downhole intercepts, not necessarily true widths, and the company notes that the deposit’s folding and faulting make drilling orientation complex.

Existing infrastructure creates a brownfields pathway

Centenary lies approximately 250m from current Rasp operations and close to the Western Min orebody, with access to existing underground infrastructure and the 750,000-tonne-per-year Rasp processing plant. BHM describes the location as offering a brownfields development pathway with materially lower capital intensity than a standalone project, although the announcement does not provide a development study, mine plan, capital estimate or production schedule for Centenary.

The potential scale is also not yet the full geological story. Recent drilling identified three additional, non-continuous lodes, known as the B, C and Gahnite lodes, but these were excluded from the Exploration Target because the drilling is still at an early stage. Further work could therefore change the geological interpretation in either direction, rather than simply add tonnes to the current estimate.

FY27 development drives precede December resource update

BHM has started a staged development program, including new exploration drives intended to test the northern Centenary extension and support infill drilling during FY27. The company expects current drilling to feed into an updated Rasp Mine Mineral Resource estimate due in December 2026, a target flagged alongside its Centenary target preview, which reported the September quarter’s production growth and said the Exploration Target was forthcoming.

The critical distinction is regulatory as well as geological: an Exploration Target is conceptual and is not a Mineral Resource. BHM explicitly says there has been insufficient drilling to estimate a resource and that further drilling may not result in conversion. The December update will therefore be the first practical test of how much of the headline target survives tighter resource definition, while continuity, metallurgy, mine design and processing capacity remain unresolved.