ASX-listed Northern Star Resources has reported a 9.4-million-ounce increase in its group mineral resources to 70.7-million ounces and a 1.4-million-ounce rise in ore reserves to 22.3-million ounces for the 12 months ended March 31, 2025, underpinned by exploration-led growth across its Tier 1 operations.

The company said the figures were achieved after accounting for mining depletion, underscoring the success of its brownfield exploration strategy and the effectiveness of its investment in resource conversion.

“Exploration remains a highly attractive lever for us to create value by adding extra resource ounces at a cost of A$20/oz, to help drive superior shareholder returns,” said Northern Star MD Stuart Tonkin. “Our team continues to generate significant increases in group gold inventory through the drill bit.”

At the Kalgoorlie Consolidated Gold Mines (KCGM) operations, mineral resources increased by 7.2-million ounces to 38.9-million ounces, while ore reserves rose by 1.2-million ounces to 14.4-million ounces, driven predominantly by extensions at the Fimiston underground.

“Our portfolio of assets across Tier 1 locations continues to deliver exploration success with a significant uplift to both group mineral resources and ore reserves,” Tonkin said. 

“At our largest asset KCGM, the mineral resources across openpit, underground and regional areas increased 23% year-on-year, while ore reserves increased 9% year-on-year highlighting the ongoing potential to extend mine life.”

Since acquiring KCGM five years ago, Northern Star has doubled its mineral resources and increased its ore reserves by 50%, at an average discovery cost of A$13/oz.

Meanwhile, a maiden mineral resource of 900 000 oz at 2.1 g/t and an ore reserve of 250 000 oz at 3.1 g/t has been declared at the Hercules discovery.

At the Jundee operation, the company has begun development of the new Griffin discovery, increasing the mineral resource by 500 000 oz to 6.4-million ounces. Infill drilling is planned to support ongoing reserve replenishment.

At the high-grade Pogo mine in Alaska, the mineral resource grade was maintained at 10 g/t, while ore reserves increased by 600 000 oz to 2.1-million ounces, supported by improved milling throughput.

Northern Star noted that the latest update did not include the Hemi project in Western Australia, acquired through the recent takeover of De Grey Mining.

“This update does not include the Hemi project, the world-class discovery we now own following the recent acquisition of De Grey Mining,” Tonkin said. “We look forward to incorporating Hemi into our gold inventory, while progressing development for what will become our fourth production centre.”

The company has also adjusted its gold price assumptions upwards while maintaining a conservative approach, in order to clearly demonstrate the impact of its exploration efforts.