Multinational mining and metals processing group Sibanye-Stillwater has written down the value of its Zimbabwe-based Mimosa platinum mine by ZAR461 million (US$28,74 million) following a June 30, 2025, life-of-mine reassessment that revised cost assumptions and incorporated a new beneficiation tax, cutting projected cash flows.
The impairment underscores the growing impact of Zimbabwe’s tightening fiscal regime and rising operating costs on foreign-owned mining assets, at a time when the government is pushing for greater mineral beneficiation and a larger share of mining revenues.
The updated assessment showed working and capital costs rising above previously assumed US dollar inflation levels, while also factoring the country’s beneficiation tax into long-term projections.
Lower anticipated cash flows reduced the mine’s value in use, prompting an interim impairment of property, plant and equipment and a downward adjustment to Sibanye-Stillwater’s equity-accounted investment in Mimosa.
No further impairment assessment was undertaken on December 31, 2025, as management identified no additional indicators of value deterioration at year-end following the June review.
The write-down comes as the 2026 National Budget pushes to enhance mining fiscal revenues and deepen domestic value addition. Treasury has signalled its intention to tighten revenue collection from the sector to increase the fiscus’ share of mineral wealth amid firming commodity prices.
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“Mimosa’s updated life-of-mine at 30 June 2025 indicated above US dollar inflationary increases in working costs and capital costs, and included a Zimbabwean beneficiation tax which resulted in a decrease in the expected future net cash flows from Mimosa,” Sibanye-Stillwater said in its financial results for the year ended December 31, 2025.
“The lower value in use led to an after-tax equity-accounted impairment of property, plant and equipment amounting to ZAR535 million and the impairment of the investment in the equity-accounted investee of ZAR64 million, before the impact of deferred tax (net an impairment of ZAR461 million).
“The weighted average PGM (4E) basket price, nominal discount rate, and life-of-mine used in the Mimosa impairment assessment was ZAR25,745/4Eoz, 20,67% and eight years, respectively. The recoverable amount at 30 June 2025 was determined as ZAR2,208 million.”
The impairment comes as local officials assured miners at the Zimbabwe Mining Forum, held on the sidelines of the 2026 Investing in Africa Mining Indaba in South Africa, that their investments remain secure.
Sibanye-Stillwater said attributable production from Mimosa declined 5% year-on-year to 117 019 4Eoz, mainly due to concentrator downtime caused by power outages, which affected recoveries.
All-in sustaining cost (AISC) rose 11% to US$1,280/4Eoz (ZAR22,894/4Eoz), primarily due to lower production volumes.
In mining, the AISC is a cost metric that shows the total cost required to sustain current production levels, which gives investors a clearer picture of what it costs to keep producing metal — not just to mine it.
Despite the operational headwinds, Mimosa posted revenue of ZAR3,61 billion during the period under review, up from ZAR3,1 billion in 2024, reflecting stronger realised prices despite lower output.
Adjusted earnings before interest, taxes, depreciation and amortisation increased to ZAR1,08 billion from ZAR619 million in the prior year, underscoring improved operating margins.
Meanwhile, capital expenditure was reduced to ZAR358 million from ZAR548 million, signalling tighter capital discipline.