- 01Porphyry Cu potential at Laleno Dome.
- 02Cu in porphyritic diorite; 0.66% Cu on outcrop.
- 03Au up to 1.3 g/t; nine Cu sites; drilling pending approvals.
Estrella Resources (ASX: ESR) has identified porphyry-style copper mineralisation at its Laleno Dome prospect in Timor-Leste, with petrographic work confirming hydrothermally altered porphyritic diorite to microdiorite.
Rock-chip assays from outcropping porphyritic intrusive rock returned up to 0.66% copper, while selected samples elsewhere around the dome produced substantially higher copper values of up to 33.22% and a previously reported 60.34%.
Gold has also been detected at up to 1.3 grams per tonne, adding another exploration indicator to a system where copper mineralisation is now known at nine locations around the northern part of the dome.
Estrella considers the combined evidence supportive of a broader intrusion-related copper-gold system, although further work is required to establish the scale, continuity, and geometry of the mineralisation.
Multiple Mineralisation Styles
Copper has also been identified in surrounding country rock, including the Noni Formation and weathered ultramafic rocks, where quartz-vein stockworks containing copper mineralisation provide further evidence of hydrothermal activity around the intrusive system.
“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,” managing director Robert Mencel said.
“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.”
Assay patterns indicate that mineralisation hosted by the Noni Formation, ultramafic rocks, and porphyritic diorite may have differing geochemical signatures, although the company notes the interpretation is based on only 15 samples and may also reflect zonation or weathering effects.
Estrella therefore considers both intrusion-related and sedimentary-style explanations possible for some of the copper occurrences, with additional sampling required to resolve the relationships between the different mineralised settings.
Drill Targets Moving Forward
Ground resistivity and induced polarisation surveys have generated additional drilling targets around Laleno Dome, with Estrella currently awaiting Timor-Leste government approval to begin drilling at priority sites.
A regional airborne magneto-telluric and magnetic survey covering Estrella’s tenure is now scheduled to start in October, with results expected before year-end to help define further drill targets and the possible subsurface extent of the intrusive rocks.
Equipment mobilisation for the regional survey is underway after logistical factors delayed its commencement, with the planned coverage to include the ground between the known mineralised outcrop and the larger dioritic exposure to the north-northwest.
Estrella plans to investigate significant reconnaissance assay results further and progress discovered mineralised occurrences of sufficient scale to drilling, with the immediate Laleno program dependent on government approval.
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