Hunt on for mineral sands in Sri Lanka’s largest limestone quarry

The Aruwakkalu area is located 25 km north of Puttalam, in the North-Western Province. It is an area considered a mainstay of Sri Lanka’s cement industry. The new plan allows valuable materials such as ilmenite, rutile and zircon to be separated from the soil layer. Experts say the deposit “is of geological and scientific importance”.

Colombo (AsiaNews) - The Aruwakkalu limestone deposit, part of the Jaffna Basin situated 25 km north of Puttalam in the North-Western Province, is at the centre of a development plan aimed at boosting its productivity.

The area is considered the backbone of Sri Lanka’s cement industry and is managed by Siam City Cement (Lanka) Limited (Insee Cement), with the primary aim of supplying the production plant in Puttalam.

The cornerstone of the new plan is a strategic shift towards a more sophisticated, multi-resource extraction model, which allows valuable mineral sands such as ilmenite, rutile and zircon to be separated from the overburden. This strategy represents a significant departure from the long-standing approach used to date, which treated the overburden simply as a waste product.

Aruwakkalu is also home to Sri Lanka’s largest open-cast limestone mine, which supplies the main raw material for the country’s cement industry.

According to senior officials at the Ministry of Industry, “although Miocene limestone has been the main focus of industrial mining activities for several decades, the government has recently shifted towards a more sophisticated, multi-resource mining model”.

This transformation, they continue, has been “consolidated by the adoption of an innovative proposal by the Cabinet requiring the submission of Expressions of Interest (EOIs) to separate valuable mineral sands such as ilmenite, rutile and zircon from the topsoil layer”.

A recent strategy, they add, which marks a significant departure from the long-standing approach that treated the overburden as a waste product. In this way, also following the guidelines of the National Mining Policy 2026, the government has adopted the principle of ‘added value’ through investments aimed at increasing export revenues, whilst applying rigorous environmental and social safeguards.”

Officials from the Geological and Mining Research Bureau (GSMB) explain that “a system will be established to ensure that all quantities of ilmenite and rutile are accounted for in a transparent and competitive manner, prioritising national interests”.

The GSMB is the only institution authorised to issue licences for exploration, extraction, trade and transport, including the monitoring of Industrial Mining Licences (IMLs). The office – they emphasise – also conducts systematic drilling and mineral surveys to assess the commercial viability of deposits, such as the limestone and mineral sands of Aruwakkalu.

When questioned by AsiaNews, Australian geologists Thushari de Mel and Asantha Kumrapperuma explain that “the limestone deposit forms part of the vast Jaffna limestone belt, dating back to the Miocene”, a geological period spanning from 23 to 5.3 million years ago. The area lies within the Northern Province, consisting mainly of calcarenite. The deposit, they add, comprises “an overburden of red soil and low-quality limestone that forms the base of a layer of high-quality limestone extending below sea level”.

“The Aruwakkalu limestone deposit,” they continue, “represents a vital resource for the cement industry, as well as a globally recognised geological and palaeontological treasure”. Its scientific importance “lies in the rich fossil record dating back to the Burdigalian (approximately 20.4–15.9 million years ago), which provides crucial clues for dating the regional limestones of Jaffna and understanding ancient marine ecosystems”. The site, Thushari and Asantha conclude, “comprises a rich fossil record of marine invertebrates and vertebrates that offers crucial insights into the ancient marine ecosystems of the Indian Ocean”.

According to academics Sampath Amarasekera and Mandana Kaluwitharana, “the Aruwakkalu limestone deposit is of geological and scientific importance as its Miocene fossil deposits include well-preserved giant oysters and gastropods”.

These geological features “are of immense value for palaeontological research and dating”. The presence of the indicator foraminifer Pseudotaberina malabarica, the index fossil of the Burdigalian Age, and other significant fossils [corals, gastropods, bryozoans and giant oysters], enables scientists to accurately date marine sequences in South Asia, they conclude, indicating “that the region was previously covered by shallow, warm, nutrient-rich tropical waters”.