Shares in Greatland Resources Ltd (AIM:GGP, OTC:GRLGF, FRA:G8G, ASX:GGP) rose 7% to 545.45p after the AIM-listed gold and copper miner reported a 150% expansion in the mineral resource at its flagship Telfer operation in Western Australia, taking the total to 8 million ounces of gold.
The updated December 2025 estimate adds 4.8 million ounces at a discovery cost of approximately $5 per ounce, with the higher-confidence measured and indicated category growing 163% to 3.8 million ounces, providing a stronger foundation for mine planning and conversion into mineable reserves.
Combined with the adjacent Havieron deposit, Greatland's total gold and copper resource now stands at 14.9 million ounces of gold and 645,000 tonnes of copper.
The resource spans open pit, underground and stockpile sources across multiple mining areas, with the West Dome Open Pit contributing 4.9 million ounces, the Main Dome Underground 2.2 million ounces and a maiden West Dome Underground resource of 0.6 million ounces at grades of approximately 2.3 grams per tonne.
The growing contribution from higher-grade underground zones is expected to play an increasingly important role in future production planning, with the West Dome Underground considered geologically analogous to the existing Main Dome Underground operation and remaining open in multiple directions.
The expanded resource base supports the long-term viability of Telfer's existing 20-million-tonne-per-annum processing plant, which Greatland took ownership of in December 2024.
Managing director Shaun Day said the combined Telfer and Havieron resource had the potential to underpin a "multi-decade, world-class mining hub."
An updated ore reserve estimate for Telfer is targeted for the second quarter of 2026, with ongoing drilling focused on converting inferred material into higher-confidence categories and extending mineralisation across key zones.
More than 134,000 metres of drilling were completed during 2025, with a further 100,000 metres planned.