Estrella Resources looks to have strengthened the case for a porphyry-style copper system at its Laleno Dome project in Timor-Leste, with new assays confirming copper mineralisation in porphyritic rocks, coupled with significant gold in the mix.
Petrographic analysis, the microscopic examination of rock slices, confirmed mineralised, hydrothermally altered porphyritic diorite. The company says the technical confirmation is a critical milestone, moving the project from a conceptual target to one backed by hard geological evidence of a large-scale intrusion-related copper-gold system.
And the surface assays certainly back that theory up. Recent rock chips returned stunning results, particularly from one sample, which graded 1.3 grams per tonne (g/t) gold, 22.6g/t silver and a whopping 45.61 per cent copper. Other samples from outcropping porphyritic intrusive rock returned up to 0.66 per cent copper.
The encouraging results stemmed from follow-up fieldwork on geophysical targets generated by a drone survey. The work expanded the mineralised footprint, with copper now identified at nine separate hotspots across the dome structure, up from four previously.
Estrella Resources managing director Robert Mencel said: "We have now identified copper mineralisation in porphyritic rock at Laleno Dome, which supports further testing of our geological model for a potential porphyry copper system along the Dome margin. Just as significantly, the rock-chip gold assay results are highly encouraging. Porphyry copper-gold systems are among the most sought-after targets in global exploration, and seeing both metals emerge together at Laleno Dome is exactly what we hoped the program would deliver.”
Estrella's geos have been building the case at Laleno Dome for some time, with the latest work suggesting the intrusive rocks could be the engine room that pumped hot, metal-rich hydrothermal fluids into the surrounding country rock, creating a widespread mineralised system.
While some of the surface copper grades are impressive on their own, including previously reported spectacular hits of 60.34 per cent and 33.22 per cent copper from selected rock chip samples, the addition of gold elevates the project’s potential significantly.
The company is now piecing together a complex geological puzzle with evidence of multiple mineralisation styles. This includes the porphyry-style mineralisation in the diorite, vein-hosted mineralisation in surrounding rocks and potential sedimentary copper styles within Timor-Leste's regional Noni Formation.
In a parallel move at Estrella's more advanced in-country projects, the company has received conditional approval from the national mining authority, the Autoridade Nacional dos Minerais (ANM), to export a maiden 100-tonne bulk sample of high-grade manganese to clients in Indonesia.
The sample was extracted from its Ira Miri open pit and has been sold at commercial market rates to a downstream customer in West Timor, intended as trial feed for a manganese smelter. The approval is an important step, with Timor-Leste's government having marked up manganese as a strategic mineral to actively attract international business.
While the 100-tonne road haulage parcel is a significant first step, it is the forerunner to a much larger play. Estrella has also lodged an application to export a 27,000-tonne bulk sample by sea and says it expects to receive that approval shortly.
Additionally, the company is pushing forward with its Werumata limestone project, also in Timor-Leste, where it recently defined a massive 621-million-tonne inferred mineral resource and has now kicked off a scoping study. Separately, Estrella is also planning a 4000-metre drilling program at the nearby Sagadate high-grade limestone project, subject to gaining approval.
Estrella is now awaiting government approval to start drilling at its priority Laleno Dome targets. In the meantime, a regional airborne geophysical survey is scheduled to run in October, helping further define the targets ahead of the much-anticipated drill campaign.
With the geological model gaining weight, the mineralised footprint growing and high-grade copper now joined by gold at surface, Estrella appears to be rounding the corner on a significant discovery. All eyes will likely be on the Timor-Leste government for the green light to get the drill rods turning.
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By Murray Ward
