Greatland Resources Limited has disclosed its Mineral Resource Estimate (MRE) for the O’Callaghans deposit, situated in Western Australia’s East Pilbara region. The report, effective as of December 31, 2025, reveals significant high-grade reserves of tungsten, copper, lead, and zinc.
2025 O’Callaghans Mineral Resource Statement
The O’Callaghans deposit, located just 10 kilometers south of the Telfer mine and entirely owned by Greatland, exhibits a mineral resource of approximately 70 million tons at noteworthy grades:
- Tungsten trioxide (WO3): 0.35%
- Copper: 0.30%
- Zinc: 0.57%
- Lead: 0.28%
This results in the following contained metal estimates:
- WO3: 246 kilotons (Kt)
- Copper: 207 Kt
- Zinc: 371 Kt
- Lead: 182 Kt
Global Significance of the O’Callaghans Deposit
O’Callaghans is recognized as one of the largest high-grade tungsten deposits worldwide. Tungsten is classified as a critical mineral by multiple countries, including Australia, the United States, and the United Kingdom, due to its essential applications in various sectors such as aerospace and defense.
Internationally, about 80% of tungsten supply comes from China, which has enacted export controls since early 2025, drastically impacting global supply and pricing. From February 2025 to now, the benchmark pricing for high-purity tungsten compounds has surged by 500%, reaching an estimated US$2,200 per metric ton unit.
Drilling and Resource Confidence
Greatland’s MRE benefits from extensive historical drilling, amounting to 71,000 meters from 184 drill holes. The majority of this drilling supports a high confidence Indicated Mineral Resource category, accounting for over 95% of the estimate.
The deposit’s geological features include a substantial skarn mineralization located at the interface between the Puntapunta Formation and O’Callaghans granite. Exploration work conducted prior to Greatland’s ownership, including a Pre-Feasibility Study by Newcrest Mining in 2020, has solidified the deposit’s economic viability.
Infrastructure Advantages
The strategic location of O’Callaghans, only 10 kilometers from the Telfer mine, allows potential synergies in infrastructure management, reducing operational costs and enhancing efficiency for mineral recovery.
Greatland’s Managing Director, Shaun Day, expressed enthusiasm regarding the deposit’s potential in the current tungsten market, highlighting the importance of O’Callaghans within the company’s broader portfolio of mining assets.
Conclusion
With the release of the December 2025 Mineral Resource Statement for O’Callaghans, Greatland Resources has positioned itself to capitalize on the growing demand for tungsten, copper, lead, and zinc. This resource estimate not only enhances its operational framework but also provides a robust foundation for future exploration and potential development in the region.
