Estrella Resources has cranked up the intrigue at its Laleno Dome in Timor-Leste after finding visible copper mineralisation within what it believes could be a porphyritic intrusive, adding a crucial new clue to its search for a potentially large hydrothermal copper system.
The find came during inspections of sites selected for imminent drilling around Laleno, a roughly 10km-wide and nearly 700m-high geological dome sitting in the middle of Estrella’s Timorese concessions. Five additional copper occurrences lifted the known tally around its northern flank to nine, with copper now observed across a 12-kilometre section of the dome margin.
The standout sample appears to be copper-hosted in an intermediate-to-felsic igneous rock that Estrella interprets as porphyritic. The sulphidic rock is hydrothermally altered, extensively fractured and cut by quartz-vein stockworks carrying traces of pyrite and malachite, a geological cocktail Estrella says supports its working hypothesis of intrusion-related mineralisation.
That possibility packs some serious punch because porphyry systems are the world’s primary source of copper and are typically large, although Estrella is yet to confirm one at Laleno.
Adding weight to the theory, Noni Formation-hosted copper occurs just 85m and 150m south-southeast of the suspected intrusive. At the same time, quartz-veined serpentinite and altered ultramafic rocks 3km south also carry the metal. Estrella believes hydrothermal fluids associated with intrusive activity may have spread into the surrounding rocks.
The geological clues also have some geophysical muscle behind them. Some of those occurrences line up with high-conductivity anomalies identified across Estrella’s 4.2km-by-3.5km Mobile Magneto-Telluric (MTd) drone survey. The company believes surface mineralisation may be an expression of larger bodies corresponding to conductive “plumes” at depth.
Eleven samples from the five new sites have been collected for assay, with results expected in late September. Ground resistivity and induced polarisation surveys have also been completed across six areas, with data processing underway. The visual copper remains subject to laboratory assays, while petrographic analysis is required to confirm the suspected porphyritic rock. The findings have nevertheless boosted Estrella’s confidence ahead of drilling.
Estrella Resources managing director Robert Mencel said: “For the first time, we have identified copper mineralisation hosted directly within what we believe to be a porphyritic intrusive. Based on these results, our upcoming drilling campaign becomes even more exciting.”
An initial 3000-metre reverse circulation and diamond-tail campaign is being prepared across three targets. Site preparation is expected to wrap up within two weeks, clearing the decks for drilling to begin in the first or second week of September in what the company says will be Timor-Leste’s deepest mineral exploration program. Additional ground geophysical surveys are also planned.
A regional helicopter magnetotelluric survey will also kick off across Estrella’s entire tenure in September, with results expected before year-end and anticipated to serve up further substantial drill targets.
Beginning active exploration in Timor-Leste in March 2024, Estrella has taken just two-and-a-half years to turn largely untouched ground into a copper story making plenty of noise.
In July, rock chips at the company's Sica prospect returned a spectacular 60.34 per cent copper and 182 grams per tonne (g/t) silver. Its Daudere target, 5km southwest, followed with up to 12.4 per cent copper and 77g/t silver, prompting Estrella to interpret a possible common hydrothermal origin across Laleno.
Copper is the wiring behind an increasingly electrified world, running through power grids, renewables and electric vehicles and into the booming power infrastructure feeding AI and data centres. As the world’s appetite for copper grows, the hunt for new discoveries is heating up and with it, the scramble to lock down future supply, giving any sizeable new system emerging from a barely explored jurisdiction plenty of reason to turn heads.
Estrella has now stitched together a 12-kilometre trail of surface copper, a suspected mineralised intrusive and a suite of geophysical targets beneath Laleno. September’s drill bit will provide the first hard test of whether those clues are pointing towards a much bigger copper system at depth.
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By Penny Taylor
