Key Highlights

  • Nine short holes totalling 285.5 metres were drilled from accessible old workings at the Emilia mine.
  • The drilling is part of the Novales zinc project in Cantabria, northern Spain.
  • The holes were drilled outside the existing resource.
  • Funding will shape how quickly systematic step-out drilling can test the broader zinc potential.

Altoro Metals (ASX:ARO) has reported results from its first modern underground diamond drilling at the historical Emilia mine, part of the Novales zinc project in Cantabria, northern Spain. Nine short holes totalling 285.5 metres were drilled from accessible old workings.

The best result came from hole EDDT001, which returned 5.00 metres at 13.66% zinc from the collar, including 1.00 metre at 25.70%. Other intercepts include 4.00 metres at 6.01% zinc in EDDT006, 5.49 metres at 5.69% in the upper part of EDDT009 and 11.00 metres at 2.79% in the upper part of EDDT008. Lead grades were generally low, although a lower interval in EDDT008 returned 3.00 metres at 3.29% zinc and 2.15% lead.

All intervals are downhole lengths, and true widths have not been established.

Context matters

These results should be read in light of how the programme was designed. A compact rig drilled short holes, mostly to test mineralisation exposed in or next to historical pillars and interpreted sulphide horizons. Altoro describes the work as confirming and improving understanding at selected positions rather than broad exploration or a greenfield discovery.

In other words, the company was drilling where miners had already found zinc in the early twentieth century. High grades at such locations are encouraging but expected; the more important question is how far mineralisation extends beyond the old workings.

On that point, the final sampled intervals in three holes, EDDT004, EDDT008 and EDDT009, returned elevated zinc grades of 3.23%, 5.97% and 6.84% respectively. Mineralisation beyond those depths has not been tested, which Altoro sees as a basis for follow-up drilling.

Core recovery caveat

Average core recovery across 98 primary samples was about 94%, but it was lower in EDDT007, averaging around 60.8% over the reported four-metre interval and 47% in the first metre. Altoro suggests friable or partly oxidised material may have been lost, which could understate grade there. The reported figure uses recovered core without adjustment, which is the conservative approach.

Why Emilia matters

Emilia lies about 2.3 kilometres north-east of the San José deposit and sits entirely outside Altoro's existing Mineral Resource. It falls within an interpreted 12-kilometre Novales-Udías zinc trend. The mineralisation is described as carbonate-hosted Mississippi Valley-type zinc-lead, a style that can form clusters of deposits along favourable horizons.

Altoro's strategy is to consolidate several deposits, including San José, Margarita, Emilia and Udías, into a single development opportunity. Novales is about 30 kilometres south-west of Santander, nine kilometres from the former Reocín mine and roughly 180 kilometres by road from the San Juan de Nieva zinc smelter.

Consolidation could offer economies of scale. Several small deposits that would struggle as standalone mines might, together, support a central processing operation, particularly with an established smelter within trucking distance. That logic only holds if each deposit can be shown to contain enough mineralisation at sufficient grade, which is why resource definition across the district is the critical next step.

Market backdrop

The announcement cited LME cash zinc of about US$3,955 a tonne on 30 October, above the three-month price, and an International Lead and Zinc Study Group forecast of a refined zinc Deficit of about 88,000 tonnes in 2026. Those figures describe current market tightness, but prices can change quickly and uneven construction Demand remains a risk.

Next steps

Altoro will integrate the nine holes with historical workings, mapping and channel sampling, refine targets around Emilia and the Emilia-Margarita area, and assess how much more drilling is needed before Emilia could contribute to a resource update. The programme is continuing, and assays for remaining holes are pending.

Altoro's ability to fund systematic step-out drilling will shape how quickly that question is answered.