Glencore's own-sourced zinc production reached 969,400 tonnes in 2025, up 7% from 2024, driven by higher grades at Antamina in Peru and a recovery at McArthur River in Australia. But the forward picture has reversed sharply. Fastmarkets reports that Glencore is guiding 2026 zinc output at 700,000-740,000 tonnes — a cut of roughly 230,000-270,000 tonnes, or 25% year-on-year. (FACT: Glencore production report 2025, Fastmarkets, LME Week 2025)
The primary driver is Antamina. The mine, operated jointly by Glencore, BHP, and Teck, is entering the final phase of its current mine plan, with zinc grades in terminal decline. Glencore's 2025 Antamina production was boosted by one-off higher grades in the transition zone — those are not expected to repeat. Post-2026, Glencore's zinc output is expected to stabilize around 720,000 tonnes per year as Antamina gradually winds down. (FACT: Fastmarkets, Glencore investor guidance)
Two other structural factors compound the decline. The Mount Isa complex's MICO mine closed in mid-2025, removing 13,300 tonnes of copper production and associated zinc by-products from the portfolio. And while McArthur River recovered in 2025 (+14,900 tonnes year-on-year), it is operating near its permitted capacity ceiling, leaving little room for further growth. (FACT: Glencore FY2025 production report)
The cut comes at a critical time. ILZSG data shows the global refined zinc market swung from a forecast surplus of 271,000 tonnes for 2026 to an actual deficit of 19,000 tonnes, following a 33,000-tonne deficit in 2025. With Glencore — the world's largest player — pulling 250,000 tonnes out of the mine supply chain, concentrate markets that were already tight are set to tighten further. The 2026 TC/RC benchmark, still unsettled as of May, is expected to settle at very low levels, with some market participants discussing negative treatment charges. (FACT: ILZSG, Fastmarkets, Reuters)
Glencore's guidance cut is structural, not cyclical. Antamina's decline is a multi-year trend, not a one-off. This removes the single largest potential source of zinc concentrate growth from the market for the next 3-5 years. If you haven't already, build the expectation of sustained LME zinc prices above $3,000/t into your 2027 procurement budget. The concentrate shortage will eventually constrain Chinese smelter output too — Chinese TCs have already fallen to ~1,600 RMB/metal-ton, and imported TCs to ~$40/dry-ton. The era of cheap zinc concentrate is over.