Why Estrella Resources (ASX:ESR) Has Updated the Werumata Limestone Resource in Timor-Leste to 533 Million Tonnes

Sonal Goyal

15 October 2026 10:45 PM AEDT

Why Estrella Resources (ASX:ESR) Has Updated the Werumata Limestone Resource in Timor-Leste to 533 Million Tonnes

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The updated Mineral Resource totals 533 million tonnes: 274 million tonnes Indicated and 259 million tonnes Inferred.
The total is below the maiden estimate of 621 million tonnes, which the company attributes solely to changes in estimated bulk densities.
No Ore Reserve is reported, and the company's presentation discloses no funding arrangements, offtake agreements or customers.

The updated estimate

Estrella Resources Limited (ASX:ESR) has released an updated Mineral Resource Estimate for the Werumata Limestone Project in Timor-Leste, prepared under the JORC Code (2012). The central estimate totals 533 million tonnes, made up of 274 million tonnes classified as Indicated and 259 million tonnes classified as Inferred. No Measured Resource or Ore Reserve is reported. The maiden estimate, released on 14 May 2026, was 621 million tonnes and was entirely Inferred.

The company attributes the 88 million tonne reduction solely to changes in estimated bulk densities, stating that the modelled mineralised Volume is unchanged. Estimated densities were lowered for two upper horizons, with the Batu Putih upper horizon falling from 1.64 to 1.07 tonnes per bank cubic metre, and raised for the lower chalk horizon from 1.30 to 1.51. The maiden estimate used a single global density variability measure, whereas domain-specific measures are now applied. The report describes density data as covering less than 3% of core length in the announcement, and approximately 2% in the technical report.

Products and ranges

Estrella divides the resource into three direct shipping products that it says require only crushing and screening. Product 1, intended for acid neutralisation, totals 391 million tonnes at an average acid neutralising capacity of 83.9%, compared with 493 million tonnes in the maiden estimate. Product 2, for industrial uses such as aerated concrete blocks, mortar and cement blending, is unchanged at 33 million tonnes. Product 3, a higher-silica material for road base, rock Fill and aggregate, rose to 109 million tonnes from 95 million tonnes.

The estimate also sets out lower and upper cases that reflect bulk density variation rather than additional resources. The lower case totals 482 million tonnes and the upper case 585 million tonnes. Roughly 70% of Product 1 is now in the Indicated category, and Indicated material represents about half of the total.

Drilling and project setting

The estimate is based on 33 reverse circulation holes for 2,804 metres and nine diamond holes for 913.1 metres, a total of about 3,717 metres, with drilling having begun on 29 October 2025. Mineralisation lies in the Baucau Limestone Formation, averaging about 30 metres thick, and the underlying Batu Putih Chalk, averaging about 26 metres. The 4,990 hectare concession lies about 170 kilometres east-north-east of Dili and is held by Estrella through its permanent representation. The report identifies open cut as the only economically feasible Mining method.

The report notes that excluding the lowest chalk horizon would reduce the central estimate to 430 million tonnes and leave only 5.5 to 6.8 million tonnes of Product 3, which may lead to a decision not to mine that horizon.

Conditions and risks

A Mineral Resource is not a reserve and does not demonstrate economic viability. Estrella states that product specifications and processing requirements remain subject to technical and customer confirmation. Its investor presentation, issued the same day, discloses no funding arrangements, offtake agreements or customers for the limestone. The competent person relied on data supplied by Estrella. The documents also contain minor inconsistencies, including two different labels for the concession licence number and a source date for the resource in the presentation that conflicts with the 14 May 2026 maiden estimate, so readers should check the original filings.

Next steps

Estrella says it will progress technical and economic evaluation of development options, advance discussions with prospective customers on specifications, offtake and applications, and continue engaging with the Timor-Leste Government on port access, infrastructure and export logistics. It also plans community engagement and will assess further drilling to test extensions and higher-quality horizons, and its presentation refers to a planned drilling campaign of about 4,000 metres, with no start date given.

FAQs

Q: What is the updated Werumata resource?

A: The central estimate totals 533 million tonnes under the JORC Code (2012), made up of 274 million tonnes Indicated and 259 million tonnes Inferred. No Measured Resource or Ore Reserve is reported.

Q: Why is it lower than the maiden estimate?

A: The maiden estimate of 621 million tonnes was entirely Inferred. The company attributes the 88 million tonne reduction solely to changes in estimated bulk densities, stating that the modelled mineralised volume is unchanged.

Q: What are the next steps?

A: Estrella says it will progress technical and economic evaluation of development options, advance discussions with prospective customers and engage with the Timor-Leste Government on port access and export logistics. It also plans to assess further drilling, with its presentation referring to a campaign of about 4,000 metres.

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