Key Highlights

  • The 18-hole aircore programme covered 1,355 metres at the Limestone Bore target.
  • One interval returned 32 metres at 1.91 per cent copper from 27 metres, including 18 metres at 3.03 per cent.
  • Limestone Bore sits more than 7 kilometres west of the other known mineralisation at Neds Creek.
  • The target was identified through shallow geochemical drilling and lies beneath transported cover.

Boa Resources (ASX:BOA) has released assays from its first aircore drilling programme at the Limestone Bore target, part of the Neds Creek copper project in Western Australia. The programme comprised 18 holes for 1,355 metres and returned copper mineralisation on two separate structures. The results represent the first drill test by Boa of a target that had previously been defined mainly through shallow geochemical sampling and historical drilling.

On an east-west trending, north-dipping structure, drilling returned 32 metres at 1.91% copper from 27 metres, including 18 metres at 3.03% copper. That result builds on a historical intersection of 10 metres at 1.28% copper recorded along the same structure.

On a second, north-north-west trending structure, one hole intersected 29 metres at 1.73% copper from 3 metres, including 9 metres at 4.77% copper. A deeper zone in the drilling returned 13 metres at 0.88% copper from 52 metres, including 3 metres at 2.40% copper. All of these are downhole widths; true widths were not reported.

Silver and a hidden setting

Boa also reported deeper silver-bearing intersections associated with carbonaceous structures, which the company likened to those at its Ricci Lee and Rooneys prospects elsewhere at Neds Creek.

Limestone Bore sits more than 7 kilometres west of the other known mineralisation at Neds Creek and lies beneath transported cover. The target was identified through shallow geochemical drilling rather than from outcrop, and the company said this points to potential for "blind" mineralisation concealed beneath younger sediments. The wider Neds Creek tenure covers 1,378 square kilometres.

Why the results matter

Finding copper under cover well away from known prospects suggests the prospective footprint at Neds Creek may be larger than previously understood. Covered terrain is often under-explored because surface sampling can miss what lies beneath, so a geochemical method that successfully located Limestone Bore could, in principle, be applied across other parts of the landholding. The shallow starting depth of the north-north-west intersection, from 3 metres, is also notable for an early-stage target, although depth alone says nothing about economics.

The presence of two mineralised orientations, plus silver associated with carbonaceous structures, gives the company several geological ideas to test. Whether these represent parts of a single system or separate occurrences is a question the next round of drilling will need to address. The comparison with Ricci Lee and Rooneys is the company's geological interpretation, and it has not yet been tested by drilling designed specifically for that purpose at Limestone Bore.

Limitations

Aircore drilling is a first-pass tool used to sample shallow and weathered material quickly and cheaply. It typically provides less reliable information on structure and geometry than reverse circulation or diamond drilling, and results can be influenced by near-surface enrichment. With no true widths, no confirmed orientation of the mineralised bodies and only 18 holes completed, the size and continuity of mineralisation at Limestone Bore remain unknown. There is no mineral resource at the target, and the results do not establish that an economic deposit exists.

Next steps

Boa said it will refine its structural model for Limestone Bore and design follow-up drilling, including the orientation and spacing of holes needed to test the two structures properly. Holes drilled across the structures should help the company estimate true widths and work out how the copper-bearing structures connect, which will be central to judging whether Limestone Bore warrants more substantial drilling.