Supply structure · the host map
Smelters, not mines
A whole tier of strategic metals is never mined for its own sake. Gallium, germanium, indium, tellurium, rhenium, bismuth, cobalt, selenium — they are recovered as by-products at copper, zinc, lead and nickel smelters. That makes the base-metal smelter, not the mine, the hidden critical-mineral infrastructure: lose the host's smelting capacity and the by-product starves, no matter how much ore exists. And China has driven over 90% of copper-smelting growth since 2005. This maps the host facilities; hostage metals is the dependency finding behind it.
The atlas's by-product mechanism says these metals cannot scale on their own — their output is bounded by a host they do not control. The IEA's own "roots of by-products" table confirms the wiring one-for-one. The strategic consequence: securing gallium or germanium is not a mining problem, it is a smelter problem — which is why China's dominance of base-metal refining quietly gates a dozen high-tech metals at once.
15% → 50%
China's share of world copper smelting, 2005 → 2025 (over 90% of all growth)
< 10%
of the gallium contained in mined ore is even recovered today — the rest is lost
5 hosts
copper, zinc, lead, nickel and aluminium carry essentially the whole by-product tier
The host map — what starves if each smelter fails
Stage is where the by-product is captured. Mining = in beneficiation; Smelting = in roasting/dross; Refining = in electro-refining anode slimes or leach residues. Grades are per tonne of ore or concentrate.
By-product optionality. Because these metals ride on a host, their supply cannot respond to their own price or a shortage — only to the host's economics. If non-China copper and zinc smelters keep closing (benchmark treatment charges hit zero in 2026, and ex-China utilisation is below 70%), the diversified world loses not just refined copper and zinc but the optionality to recover gallium, germanium, indium, tellurium and rhenium anywhere else. The smelter is the chokepoint behind a dozen chokepoints.
Source: IEA, Global Critical Minerals Outlook 2026 — "Roots of by-products" annex (pp. 367-368), copper-smelter concentration (pp. 130-133), strategic-minor-minerals section. © IEA, CC BY 4.0. Corroborates the atlas's companionality and host-coupling analyses built independently from USGS + Nassar (2015).