SIBANYE STILLWATER LIMITED - Sibanye-Stillwater Mineral Resources and Mineral Reserves declaration as at 31 December 2025
What this filing means
Sibanye-Stillwater's 2025 reserve declaration shows strategic growth in PGM, uranium, and copper offset by a significant gold writedown at Kloof and a 44% collapse in zinc reserves.
Sibanye-Stillwater updated its list of underground minerals. While they found more platinum, uranium, and copper, they had to cancel a large portion of their gold reserves at the Kloof mine because it is no longer economical to dig up. They also have very little zinc left to mine, meaning that part of the business will slow down soon unless they find new projects.
Bull case
- SA PGM Mineral Reserves increased by 4.7% to 29.4Moz, driven by the inclusion of 2.9Moz from the Marikana E4 mechanised UG2 project.
- Declared maiden Mineral Reserves for uranium (25.2Mlb) and copper (478kt) following the completion of key feasibility studies.
- Lithium Mineral Resources at the Keliber project grew by 8.4% to 510kt LCE due to successful exploration at Leviäkangas and Tuoreetsaaret.
- Significant upward revision of long-term price assumptions for gold ($2,421/oz) and uranium ($90/lb) improves project economics.
Bear case
- Major writedown of 1.4Moz in gold Mineral Reserves at Kloof due to geotechnical constraints and production viability issues.
- Zinc Mineral Reserves plummeted 44.2% at the Century operation, leaving only approximately 18 months of remaining reserve life.
- Complete divestment from the Ioneer Rhyolite Ridge project and 50% dilution at the Altar project indicates a retreat from previous battery metal growth targets.
- Aggressive long-term price assumptions may artificially inflate reserve figures and increase the risk of future impairments.
AI-generated summary by SENS-AI, based on the original JSE SENS filing.
SENS-AI conclusion
Sibanye-Stillwater has delivered a high-variance update that highlights its successful transition into a multi-commodity player with maiden uranium and copper reserves, yet underscores the structural decay of its mature SA gold assets. The 1.4Moz writedown at Kloof and the 18-month 'cliff' in zinc reserves at Century are significant operational headwinds that partially negate the 4.7% growth in PGM reserves. Investor Takeaway: While the maiden reserves provide long-term optionality, the immediate loss of gold reserves and looming zinc depletion suggest a high-cost profile that justifies the stock's current discount below its 50-day moving average. Signal-to-Price Note: The price is down despite the 'maiden reserve' headlines, likely because the market is focusing on the 44.2% drop in zinc reserves and the geotechnical failure at Kloof.
Evidence from the filing
Attributable SA PGM Mineral Reserves increased by a robust 4.7% year-on-year to 29.4Moz, significantly bolstered by the inclusion of 2.9Moz from the Marikana E4 mechanised UG2 project after its feasibility study completion.
“4E PGM Mineral Resources of 177.3Moz (-2.0%) and Mineral Reserves of 29.4Moz (+4.7%) at our SA PGM operations – The inclusion of the Marikana E4 mechanised UG2 project Mineral Reserves added +2.9Moz to Mineral Reserves following the completion of a feasibility study”
The successful completion of feasibility studies led to the declaration of maiden Mineral Reserves for critical future-facing commodities, including 25.2Mlb of Uranium Oxide (U3O8) from the Cooke TSF project and 478kt of Copper from the Mt Lyell project.
“Uranium Oxide (U3O8) Mineral Resources of 59.3Mlb (+0.1%) and Mineral Reserves of 25.2Mlb at our SA gold operations – The maiden uranium Mineral Reserve is based on the completion of the Cooke TSF feasibility study”
Lithium Mineral Resources at the Keliber project in Europe showed an encouraging year-on-year increase of 8.4% to 510kt lithium carbonate equivalent (LCE), driven by successful exploration activities and updated resource estimates.
“LCE Mineral Resources of 510kt, a year-on-year increase of +8.4% – The increase in Mineral Resource is due to ongoing, successful exploration activities which led to the identification of further mineralisation at the Leviäkangas and Tuoreetsaaret deposits. This prompted a Mineral Resource estimate update (+40kt).”
Management's long-term price assumptions for key metals underpinning Mineral Reserves are significantly higher year-on-year, with gold at US$2,421/oz (up from US$1,750/oz) and uranium oxide at US$90.00/lb (up from US$63.00/lb), indicating a strong conviction in future commodity markets and enhanced project economics.
“Price assumptions as at 31 December 2025 for managed Mineral Resources & Mineral Reserves (excluding SA gold Mineral Reserves) ... Gold1 ... 2,421 [US$/oz] (2025) ... 1,750 [US$/oz] (2024) ... Uranium oxide (U3O8)2 ... 90.00 [US$/lb] (2025) ... 63.00 [US$/lb] (2024)”
The substantial writedown of gold Mineral Reserves at the Kloof operation due to production constraints, including geotechnical considerations and the exclusion of high-grade resources, signifies a structural decline in the quality and quantity of core SA gold assets, impacting future production and inherent value.
“At the Kloof operation, production constraints, including geotechnical considerations which led to the removal of isolated blocks of ground, have impacted the economic viability of the operation, leading to a writedown of the majority of the Mineral Reserves (-1.4Moz)”
Sibanye-Stillwater has adopted significantly inflated long-term commodity price assumptions, notably increasing gold from US$1,750/oz to US$2,421/oz and uranium from US$63.00/lb to US$90.00/lb for reserve calculations, which could artificially bolster reported reserves and lead to future impairments if prices revert to historical averages.
“Price assumptions as at 31 December 2025 for managed Mineral Resources & Mineral Reserves (excluding SA gold Mineral Reserves) ... Gold1 Long term (2030 onwards) US$/oz 2,421 ... (31 Dec 2024) US$/oz 1,750”
The complete divestment from the Ioneer Ltd joint venture for the Rhyolite Ridge Lithium-Boron project and the 50% reduction in attributable interest at the Altar copper project signal a concerning retreat or dilution in the company's strategic battery metals diversification efforts, raising questions about capital allocation efficiency and future growth drivers.
“As announced on 26 February 2025, Sibanye-Stillwater chose not to proceed with Ioneer Ltd in the joint venture to develop the Rhyolite Ridge Lithium-Boron project. The Group also divested of its 6.19% equity interest in Ioneer Ltd, resulting in no attributable Mineral Resources being recognised.”
The Century zinc operation faces an imminent revenue cliff, with Mineral Reserves plummeting by 44.2% year-on-year and only approximately 18 months of reserve life remaining, posing a significant risk of lost cash flow and underutilised infrastructure unless speculative regional phosphate mining partnerships materialise quickly.
“Zinc Mineral Reserves of 308kt, a year-on-year decrease of -44.2%”
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