Regis Resources Extends Mine Life with 120% Reserve Growth at Garden Well Underground

Garden Well Underground Drives Reserve Expansion

Regis Resources (ASX:RRL) has unveiled a robust Mineral Resource and Ore Reserve update for 2025, with the Garden Well Underground operation stealing the spotlight. After accounting for mining depletion, Ore Reserves at Garden Well surged by over 257,000 ounces, a staggering 120% increase to 474,000 ounces. This leap not only extends the mine life materially but also underscores the quality of the deposit and the effectiveness of Regis’ geological and technical teams.

Since declaring its initial underground Ore Reserve in 2019, Regis has amplified Duketon’s total underground Ore Reserves by approximately 480%, with Garden Well’s Indicated Resources alone climbing from 260,000 to 479,000 ounces. The company credits this sustained growth to a disciplined, systematic approach to discovery and reserve conversion, backed by deepening geological knowledge.

Continued Underground Growth at Rosemont and Tropicana

At Rosemont, the more mature underground operation within Duketon, Regis again outpaced mining depletion, adding 83,000 ounces to Mineral Resources after accounting for 55,000 ounces mined, resulting in a total of 473,000 ounces. This growth is supported by newly classified Inferred mineralisation to the south, signaling a healthy pipeline for ongoing reserve replacement.

Meanwhile, Tropicana’s underground Ore Reserves grew by 210,000 ounces net of depletion, achieving a 106% replacement rate. Since its initial underground Ore Reserve declaration in 2018, Tropicana’s underground reserves have more than doubled, reinforcing the asset’s world-class status and long-term value. This aligns with Regis’ confidence that underground Ore Reserve growth will at least match depletion over the long run, a view elaborated in their recent underground Ore Reserves at Tropicana report.

Southern Star Debuts as Emerging Resource

Adding to its pipeline, Regis announced an initial Mineral Resource Estimate for Southern Star, a deposit acquired in mid-2025 along the prolific Rosemont–Ben Hur structural corridor. Although early stage and not yet material on a standalone basis, Southern Star’s 1.1 million tonnes at 1.1 g/t gold for 69,000 ounces adds to the company’s growing resource base in Duketon South. Regis is actively evaluating Southern Star’s potential to convert resources to Ore Reserves, consistent with its strategy of sustaining resource and reserve growth.

Open Pit Reserves and Economic Assumptions

On the open pit front, Duketon’s Ore Reserves rose modestly to 675,000 ounces after depletion of 150,000 ounces, incorporating incremental ounces from various surface projects. Regis employs conservative economic assumptions underpinning its resource and reserve estimates, including a long-term gold price assumption of A$3,900 per ounce for Mineral Resources and A$3,500 per ounce for Ore Reserves. These assumptions are complemented by detailed JORC-compliant technical disclosures, ensuring transparency and confidence in the estimates.

Regis’ Managing Director Jim Beyer emphasised the value of the geological team’s systematic approach, noting the ongoing underground potential at both Duketon and Tropicana. The company’s consistent track record of reserve growth amid depletion highlights operational discipline and exploration success.

Capital and Operational Implications

While the update does not provide explicit production guidance or detailed cost changes, the significant reserve additions at Garden Well and Tropicana suggest a potential extension of mine life and sustained underground production. This is particularly relevant given the company’s recent cash and bullion build amid production shortfall reported in April 2026, where Regis increased its cash reserves despite trailing production guidance. The reserve growth may provide a buffer and optionality for future operational planning and capital allocation.

The disciplined reserve replacement at these key assets will be critical to monitor as Regis navigates ongoing operational challenges and market conditions. The Southern Star resource also presents an intriguing early-stage opportunity that could add incremental value if successfully advanced.