Estrella finds porphyry-style copper and gold at Laleno Dome

Porphyritic rock adds weight to Laleno copper model

Estrella Resources Limited (ASX:ESR) has found the geological feature it needed to make Laleno Dome more than a collection of striking surface samples: copper mineralisation hosted in altered porphyritic intrusive rock. Three rock-chip samples from the outcrop returned up to 0.66% copper, including 0.66% in sample ESR006494 and 0.53% in ESR006498, with the latter also returning 1.4 parts per million silver.

Petrographic analysis of six samples classified the rock as variably porphyritic diorite to microdiorite, a sub-volcanic intrusive rock affected by chlorite-sericite alteration, quartz-carbonate veinlets, silica flooding and pyrite. Those features are consistent with Estrella’s interpretation that porphyry-style copper mineralisation may be present, although the filing stops short of establishing a deposit or demonstrating continuity.

Nine copper occurrences and a new gold signal

Field inspections around Mobile Magneto-Telluric drone survey targets have now identified copper at nine locations around the northern part of the dome, including five newly recognised occurrences. Gold was also detected in the latest batch, reaching 1.3 grams per tonne in sample ESR006492, while silver and copper were present in several samples from the Noni Formation and weathered ultramafic rocks.

The headline grades need careful handling. Previously reported sample ESR006095 assayed 60.34% copper, while new sample ESR006491 returned 33.22% copper. Estrella states that the selected rock-chip specimen from ESR006491 is not representative of the broader outcrop, and the announcement makes the same broader point about reconnaissance sampling: samples were selective, grab or composite specimens intended to confirm mineralisation at particular points, not to measure thickness, grade distribution or resource potential.

Mineralisation origins remain unresolved

Estrella’s preferred interpretation is that a dioritic intrusion generated hydrothermal fluids, producing copper within the intrusion and in peripheral rocks. Quartz-vein stockwork and copper-bearing veinlets in ultramafic rock support that possibility. Copper in the Noni Formation could also have been introduced by those fluids, but the company acknowledges an alternative explanation: a separate sedimentary copper style.

The distinction is not academic. The comparison is based on only 15 samples from earlier and current batches, all derived from strongly weathered material. Differences in elements such as silver, arsenic, cobalt, selenium and tellurium may reflect separate mineralisation styles, zonation, or the redistribution of metals during weathering. More representative sampling and drilling will be needed before the competing explanations can be tested with confidence.

Drilling depends on approval and geophysical follow-up

Estrella is awaiting Timor-Leste Government approval to drill priority Laleno Dome targets generated by ground geophysics and the Mobile MTd survey. A regional helicopter-based Magneto-Telluric and magnetic survey is scheduled to begin in October 2026, with results expected before year-end and intended to help define additional drill targets. The company has not reported drilling results from Laleno Dome.

Elsewhere in the portfolio, Estrella is planning a 4,000-metre combined reverse-circulation and diamond drilling programme at the Sagadate high-grade limestone project, subject to approvals and operational progress. It is also preparing a maiden manganese trial parcel from the Ira Miri stockpile, with export approval lodged and a sales agreement conditional on that approval. For Laleno, however, the next decisive evidence will come from holes that show whether the attractive surface chemistry has scale, continuity and geometry beneath the cover.