Greatland Resources Defines 70 Million Tonne Tungsten Resource at OCallaghans Deposit

Greatland Resources Ltd has announced a maiden mineral resource estimate for its OCallaghans tungsten-copper-zinc-lead deposit in Western Australia, marking a significant addition to the company’s Paterson Province portfolio. The resource totals 70 million tonnes at 0.35 per cent tungsten trioxide, accompanied by 0.30 per cent copper, 0.57 per cent zinc and 0.28 per cent lead. The deposit now ranks amongst the largest high-grade tungsten resources globally outside China, Russia and North Korea.

The resource estimate forms part of Greatland’s broader December 2025 Group Mineral Resource release, which also included substantial upgrades at the Telfer gold-copper operation and reinforced the scale of the company’s Paterson Province holdings.

OCallaghans introduces a critical minerals dimension to Greatland’s predominantly gold-copper focused portfolio. Tungsten has gained increasing recognition as a strategic commodity across major economies, owing to its extreme hardness and heat resistance properties which render it difficult to substitute in applications ranging from mining and construction to aerospace and defence. Industry data suggests aerospace and defence sectors account for approximately one quarter of global tungsten demand.

Supply fundamentals have tightened considerably. China, responsible for roughly 80 per cent of global tungsten production, implemented export controls in early 2025 and has subsequently transitioned from net exporter to significant importer. This shift has contributed to a marked increase in benchmark tungsten prices, providing a supportive backdrop for new resource development outside traditional supply centres.

The geological confidence underpinning the resource estimate is particularly noteworthy. More than 95 per cent of the 70 million tonne resource sits within the higher-confidence Indicated category, supported by approximately 71,000 metres of drilling across 184 holes at roughly 100-metre spacing. Contained metal estimates include 246,000 tonnes of tungsten trioxide, 207,000 tonnes of copper, 371,000 tonnes of zinc and 182,000 tonnes of lead.

The polymetallic nature of the deposit provides multiple potential revenue streams. Mineralisation is hosted in a skarn system located approximately 300 metres below surface, with the deposit positioned just 10 kilometres south of the existing Telfer processing hub.

This proximity to established infrastructure represents a potentially significant advantage. Whilst OCallaghans does not constitute the company’s immediate development priority, its location relative to Telfer could facilitate future development pathways leveraging existing logistics, workforce and site infrastructure. Historical work on the project includes a pre-feasibility study completed by a previous owner, which outlined a long-life underground mining operation with dedicated processing plant and downstream tungsten refining capability.

The resource estimate arrives as Greatland continues to expand its gold-copper inventory substantially. According to the group update, Telfer’s resource has grown to 8.0 million ounces of gold, whilst the combined Telfer and Havieron inventory now stands at 14.9 million ounces of gold and 645,000 tonnes of copper. Within this context, OCallaghans represents a complementary asset offering diversification into critical minerals whilst the company maintains its primary focus on gold and copper development.

Managing director Shaun Day noted the deposit presents latent value and optionality within Greatland’s portfolio, particularly given prevailing tungsten market conditions.

Greatland has indicated its immediate priority remains advancing Telfer and the Havieron development, though the scale and quality of the OCallaghans resource provides a clear foundation for future evaluation. The company is assessing pathways to demonstrate and enhance the project’s value, potentially including further technical studies, partnerships or staged development options.

With underlying demand for critical minerals remaining robust and global supply dynamics tightening, OCallaghans adds a strategic dimension to Greatland’s broader growth strategy in the Paterson Province. The resource provides exposure to tungsten markets at a time when Western economies are increasingly focused on securing supply chains for materials deemed critical to defence and advanced manufacturing applications.