Substitutability in Criticality Assessments
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The EU scores substitution with an index in which 1.00 means no proven substitute and lower values mean substitutes already in use. The 2023 study gives values from 0.59 for gadolinium to 1.00 for manganese, molybdenum and titanium metal, and it counts only substitutes that are proven and readily available today, not ones that might exist in future. Most materials in the study score above 0.85, so substitution changes a score only a little for most of them.
0.59
gadolinium's substitution index, the lowest in the EU 2023 study; manganese, molybdenum and titanium metal score 1.00
0.70
copper's substitution index for economic importance (0.71 for supply risk), the second lowest of all materials in the study
0.99 to 0.90
change in natural rubber's substitution parameter in 2023, one of two changes that took its supply risk below the threshold
0.98
gallium's substitution index for both economic importance and supply risk
How does the EU measure substitution?
The EU measures substitution with two indexes, one for economic importance and one for supply risk. In the EU method, the economic importance index reflects the cost and performance of substitutes for each application and their sub-shares, and the supply risk index reflects the production, criticality and co-production of the substitutes themselves. A substitute that is itself scarce or produced as a coproduct therefore gives less relief in the supply risk index. Since the 2017 assessment the method counts only proven substitutes that are readily available today and would change the consequences of a disruption, so substitution counts but substitutability or potential future substitution does not.
The study warns that the inputs are thin. Public data on the shares of substitutes are hard to find because there are very few cases where substitutes are already used in practice, so many sub-shares rest on expert assumptions.
What do the 2023 substitution indexes show?
The table lists the index for each score and what USGS says about alternatives in its 2026 chapters. The USGS notes are descriptions of what is technically possible, not the inputs to the EU index.
| Material | Index, economic importance | Index, supply risk | What USGS says about substitutes |
|---|---|---|---|
| Gadolinium | 0.59 | 0.59 | Not covered separately by USGS. The EU index fell after the applications were updated toward magnets and away from lighting. |
| Copper | 0.70 | 0.71 | Aluminum substitutes in radiators, power cable and electrical equipment; optical fiber substitutes in telecommunications. |
| Zinc | 0.77 | 0.80 | Aluminum and plastics replace galvanized sheet in cars; aluminum and magnesium alloys replace zinc die-casting alloys. |
| Indium | 0.87 | 0.89 | Antimony tin oxide, carbon nanotubes, PEDOT and graphene have been developed as alternatives to indium tin oxide coatings. |
| Tellurium | 0.87 | 0.94 | Several materials can replace it in most uses, usually with losses in efficiency or product characteristics. |
| Vanadium | 0.90 | 0.92 | Other alloying metals are interchangeable to some degree in steel; no acceptable substitute in aerospace titanium alloys. |
| Germanium | 0.92 | 0.94 | Silicon or gallium arsenide in certain electronics; chalcogenide glass in infrared applications. |
| Niobium | 0.93 | 0.96 | Substitutes exist, but a performance loss or higher cost may ensue. |
| Tungsten | 0.95 | 0.96 | Most substitutes for cemented carbides reduce rather than replace the amount of tungsten used. |
| Cobalt | 0.97 | 0.98 | Cobalt-free iron-phosphate batteries held significant market share in China; other uses lose performance or cost more. |
| Natural graphite | 0.97 | 0.98 | Synthetic graphite competes in battery applications and in iron and steel production. |
| Gallium | 0.98 | 0.98 | Silicon competes in some uses, but no effective substitutes exist for GaAs and GaN in many defense-related applications. |
| Rhenium | 0.98 | 0.99 | One iridium and tin catalyst has achieved commercial success; other metals are being evaluated. |
| Manganese | 1.00 | 1.00 | No satisfactory substitute in its major applications. |
| Molybdenum | 1.00 | 1.00 | Little substitution in its major application in steels and cast irons. |
| Titanium metal | 1.00 | 1.00 | Few materials match its strength-to-weight ratio and corrosion resistance; aluminum, composites and steel compete in some uses. |
Sources: European Commission, Study on the Critical Raw Materials for the EU 2023, substitution index table; USGS Mineral Commodity Summaries 2026 chapters on copper, zinc, indium, tellurium, vanadium, germanium, niobium, tungsten, cobalt, graphite, gallium, rhenium, manganese, molybdenum and titanium. Other materials with an index of 1.00 for both scores include erbium, europium, holmium, lutetium, thulium, ytterbium and coking coal.
How much can a substitution index change a result?
A substitution index moves a score only when it changes by a lot or alongside other parameters. Natural rubber's supply risk fell below the EU threshold in 2023 because its recycling input rate rose from 1% to 5% and its substitution parameter fell from 0.99 to 0.90 on revised substitution possibilities, even though the EU still imports all of its natural rubber. Gadolinium's supply risk and economic importance dropped mostly because its substitution index decreased for the updated applications. For most materials the index sits close to 1.00, so it changes the result little compared with concentration, import reliance or sector value added.
Substitution is also not free. USGS says that for tungsten, niobium and cobalt substitution can cost performance or money, and that for tungsten most options reduce rather than replace the metal. The substitution and thrifting page covers where substitution has actually happened, such as lithium iron phosphate batteries.
Frequently asked questions
What is a substitution index?
A substitution index is a number, at most 1.00, that the EU applies to a material's economic importance and to its supply risk. A value of 1.00 means no proven substitute exists, and lower values mean substitutes are already used in practice and soften the effect of a disruption.
Which materials have no substitute in the EU data?
Manganese, molybdenum, titanium metal and coking coal score 1.00 for both economic importance and supply risk in the EU 2023 study, together with the rare earths erbium, europium, holmium, lutetium, thulium and ytterbium.
Does the EU count future substitutes?
No. Since 2017 the EU counts only proven substitutes that are readily available today, so substitution is counted but substitutability or potential future substitution is not. A promising technology that is not yet in use does not lower a score.
Why is gallium's substitution index so close to 1?
Gallium scores 0.98 for both economic importance and supply risk. USGS reports that silicon competes with gallium arsenide in some uses, but that no effective substitutes exist for gallium arsenide and gallium nitride in many defense-related applications, which is consistent with an index near 1.
Sources
Read on October 13, 2026. Figures on this page come from these documents; where a number is an estimate, the source says so.
- European Commission: Study on the Critical Raw Materials for the EU 2023. Methodology figure, glossary definition of substitution, data-availability notes and substitution index table
- USGS Mineral Commodity Summaries 2026: Substitutes paragraphs (15 chapters). Each chapter is linked under the table
