Estrella homes in on potential 500Mt Timor-Leste limestone play

Estrella Resources has just leapt another hurdle at its Werumata limestone project in Timor-Leste, with the receipt of its full suite of assays from last year’s maiden drilling campaign.

The 2025 campaign comprised 33 reverse-circulation (RC) and nine diamond drill holes for a total of 42 holes for 3717 metres across two extensive limestone plateaus near the coastal town of Uero-Mata, a potential port area.

Most notably, the final results reinforce the company’s earlier first-pass data released in February, which flagged broad, low-impurity limestone intercepts and put a potential 500-million-tonne inferred resource target firmly on the radar.

The drilling intercepted good, continuous thicknesses of Baucau limestone, up to 87m thick and averaging 30m, while the underlying Batu Putih Chalk intersections were up to 59m thick and also averaged 30m depth.

Estrella says the younger Baucau limestone averaged 33.15 per cent calcium, or 83 per cent calcium carbonate, while the Batu Putih Chalk averaged 31 per cent calcium or 77.5 per cent calcium carbonate.

Remarkably, unlike many marine limestones, the Baucau magnesium levels were low, averaging only 2.05 per cent magnesium oxide, accompanied by low alumina content at only 1.83 per cent and iron oxide at 0.96 per cent.

Estrella says the overall combined composition points to a clean lime that could be well-suited to industrial acid-neutralisation applications.

Estrella continues to develop highly exciting prospects in the virtually unexplored region of Timor-Leste and we are very pleased to report the remaining assay results from the Werumata limestone project. The results confirm the presence of a large amount of limestone and chalk, evident from broad intersections of clean lime with low impurities.

The drilling program also helped firm up the local stratigraphy, with Estrella highlighting a variable marl unit beneath the limestone and chalk sequences.

Marl is an ancient yet still-used term for an earthy mixture of fine-grained minerals, often found across a wide range of sedimentary rocks.

It is a natural soil conditioner and fertiliser made up largely of clay and calcium carbonate that has been used for centuries to neutralise acidic soils, improve soil structure and lift crop yields.

The company says the new information on the limestone stratigraphy – or its interlayering – is a useful addition to its understanding of Timor-Leste’s geology, which will underpin its upcoming modelling.

The next area of investigation is the bulk density of the materials of interest. Estrella is working with the Universidade Nacional Timor Lorosa’e (UNTL) to complete the required measurements.

The full suite of density measurements is expected to land with consultants before the end of March, in time for Estrella’s planned maiden mineral resource estimate pencilled in for mid-April.

In May last year, the company pulled off what could prove to be a genuinely game-changing deal on its carbonate product.

Estrella inked a binding master agreement with Indonesian mining and energy services outfit PT Raka Energi Mandiri (REM), handing the group exclusive marketing and off-take rights to its high-grade calcite-rich limestone.

To further align the deal, REM will receive up to 500 million performance-based share options exercisable at five cents per share if Estrella succeeds in shipping the full 500Mt of limestone within five years of first production.

To drive the strategy, the parties have formed a joint venture company, Estrella Murak Rai Timor Lda. Estrella holds a dominant 70 per cent stake while Timor-Leste’s state-owned Murak Rai Timor owns the remaining 30 per cent. The joint venture will capture 100 per cent of the revenue generated from limestone sales.

At the time, management described the agreement as “truly transformational”, with REM tasked with lining up customers in Indonesia, where demand for limestone is exploding. The material plays a critical role in neutralising acid during nickel processing - a key step in Indonesia’s massive and rapidly expanding nickel industry - as well as a range of other industrial applications.

If the numbers stack up, Werumata could soon shape up as a serious bulk limestone play with a handy coastal location suited to port infrastructures - and that’s a combination the market is unlikely to ignore.

Is your ASX-listed company doing something interesting? Contact: matt.birney@wanews.com.au