Mimosa Mining Company is facing rising production costs despite a strong increase in platinum group metals prices, with output falling during the first half of 2026.
According to results from shareholder Sibanye-Stillwater, Mimosa’s attributable PGM production dropped 7% to 55,002 4E ounces in the six months to June, from 59,054 ounces during the same period in 2025.
At the same time, sustaining capital expenditure increased from US$9 million to US$15 million. In rand terms, spending rose from R160 million to R245 million.
The mine also recorded higher costs despite receiving much better prices for its metals.
Mimosa’s average PGM basket price increased by about 82%, from US$1,317 per 4E ounce in H1 2025 to US$2,393 in H1 2026.
However, its all-in sustaining cost (AISC) rose 23%, from US$1,193 to US$1,465 per 4E ounce.
Operating costs also increased, moving from US$94 to US$105 per tonne.
Sibanye-Stillwater attributed the higher AISC to increased input costs caused by inflation, lower production, higher royalties linked to stronger PGM prices and increased sustaining capital expenditure. The impact was partly reduced by higher by-product credits.
Mimosa also processed less ore during the period. Throughput declined from 723,000 tonnes in H1 2025 to 701,000 tonnes in H1 2026.
The plant head grade fell from 3.39 grams per tonne to 3.28g/t, while recovery declined slightly from 74.98% to 74.37%.
Yield also dropped from 2.54g/t to 2.44g/t.
Sibanye-Stillwater said the decline in attributable production was mainly caused by lower feed volumes and grades, which also affected recoveries.
The figures show a combination of lower production and higher costs, despite a much stronger PGM price environment.
There was also a notable difference between production and concentrate sales. While attributable PGM production fell 7%, concentrate sales increased by 32%.
Sibanye-Stillwater said the comparison was influenced by Zimbabwe’s suspension of concentrate exports during April and May 2025.
The different export conditions make year-on-year comparisons more complicated and may have affected the timing of concentrate sales. The published results, however, do not provide enough information to determine the full reasons for the gap.
Mimosa’s inventory levels, shipment schedules and concentrate movements could therefore provide additional context on the difference between production and sales.
Despite the weaker operating performance, Sibanye-Stillwater increased the carrying value of its investment in Mimosa.
The company recorded an after-tax impairment reversal of R581 million during H1 2026. Before deferred tax, the reversal was R783 million.
Sibanye-Stillwater said the reversal followed an updated life-of-mine plan that showed higher expected future net cash flows, mainly because of stronger commodity prices since December 2025.
The carrying value of its equity-accounted investment in Mimosa consequently increased to R4.424 billion at June 2026, compared with R3.784 billion at December 2025 and R3.700 billion at June 2025.
Sibanye-Stillwater said the updated life-of-mine plan reflected an increase in expected future net cash flows due to higher commodity prices.
The impairment reversal therefore reflects a stronger valuation of Mimosa’s future cash-generating potential, rather than an improvement in its production performance during the first half of the year.
Mimosa’s H1 2026 results present a mixed picture. Production and throughput declined, grades and recovery weakened, while operating costs and AISC increased.
At the same time, sustaining capital spending rose sharply, the PGM basket price increased substantially and concentrate sales were higher.
The mine’s investment value also improved following the impairment reversal, highlighting the difference between Mimosa’s weaker short-term operating figures and the more positive long-term outlook reflected in Sibanye-Stillwater’s valuation.
