Sibanye-Stillwater holds interests in two exploration stage projects in the Americas, Altar and Marathon, which we are advancing through strategic relationships with focused exploration companies.
A closer look
The Altar exploration project is a shallow to intermediate depth copper-gold porphyry deposit located in San Juan province, Argentina, approximately 10km from the Argentine-Chile border and 180km west of the city of San Juan. Sibanye-Stillwater acquired the Altar project in 2017 as part of the Stillwater acquisition. Aldebaran Resources entered into a JV agreement with Sibanye-Stillwater in 2018 to acquire a 60%, and eventually 80%, interest in the Altar project, subject to funding certain exploration expenditures. Aldebaran Resources also assumed management of the JV.
After the incorporation of successful exploration drilling data, Aldebaran, the project manager, published an updated Mineral Resource estimate, effective 31 December 2024. The new estimate totals Measured and Indicated Mineral Resources of 2.40 billion tonnes, with grades of 0.42% copper, 0.07 g/t gold, 1.22 g/t silver, and 42 g/t molybdenum.
During 2025, Aldebaran Resource crossed the agreed financial spend threshold to earn an 80% interest in the Altar project from Sibanye-Stillwater (up from 60% as at 31 December 2024).
Also during 2025, Aldebaran Resources completed a preliminary economic assessment (PEA) on the Altar deposit, and filed an NI 43-101 technical report on SEDAR. The study envisages an initial open pit mine, with a subsequent parallel underground operation, with combined LoM of 48 years and LoM average annual production of 101.4kt of CuEq (92.8kt Copper; 27.0koz of gold and 0,5Moz ounces of silver).
In addition, Aldebaran completed ~19,000m of exploration drilling in their 2024-2025 field season, mainly aimed at enhancing the Mineral Resource confidence.
Latest news:
- 15 April 2025: Aldebaran Provides Update on Altar Field Program, PEA and Earn-In Agreement With Sibanye-Stillwater
For more information, see the Aldebaran Resources website:
The Marathon project is an advanced stage PGM-gold-copper exploration project, located approximately 10km north of the town of Marathon, Ontario, Canada, situated adjacent to the Trans- Canada Highway No 17 on the north-east shore of Lake Superior. The project is at FS level.
Exploration for copper and nickel deposits in the greater Marathon area started in the 1920s and continued until the 1940s with the discovery of several titaniferous magnetite and disseminated chalcopyrite occurrences. During the past four decades, the Marathon PGM-copper project has undergone several phases of exploration and economic evaluation, including geophysical surveys, prospecting, trenching, a diamond drilling programme, geological studies, resource estimates, metallurgical studies, mining studies and economic analyses.
As at 31 December 2025, Sibanye-Stillwater owned an effective attributable share of 12.14%, via its equity interest in Generation Mining Ltd.
During 2025, Generation Mining advanced the Marathon project by:
- Receiving the remaining outstanding permitting, including all three outstanding approvals under the Lakes and Rivers Improvement Act in respect of infrastructure construction associated with the water management structures; and the Environmental Compliance Approval – Industrial Sewage Works, making the project construction ready, bar financing
- Completing a feasibility study update and filing an updated National Instrument 43-101 technical report
- Securing a support letter from a leading Canadian financial institution stating its interest to provide up to $200 million in a new long-term credit facility, which would be in addition to the senior secured project finance facility to be arranged with the mandated senior lenders
- Acquiring 451 contiguous mining claims to its prior land package
Generation Mining has published Mineral Reserves for the project on the back of the study outcome. Sibanye-Stillwater is only publishing attributable Mineral Resources until such stage as the project has been fully funded and approved for construction. For more detail on the project, please visit https://genmining.com/projects/feasibility-study/
As at 31 December 2025, Marathon contained 33.3 million tonnes of declared attributable mineral resources at 0.21% copper and 0.7 g/t 2E+Au PGMs (68kt of copper and 0.7 million ounces of 2E+Au PGMs).
