In this paper, we present a critical raw materials index (CRMI) that represents the price dynamics of the raw materials required for the low-carbon transition. Using a unique market and trade dataset covering 29 critical raw materials from 2012 to 2023, we construct a weekly trade weighted price index following a robust methodological framework. The relevance of our index is demonstrated through a validation process including a plausibility analysis and a comparability analysis. In addition, a sensitivity analysis provides empirical evidence of the robustness of our index to alternative data treatment, weighting factors and weighting schemes. Our framework offers policymakers a useful price benchmark to track the underlying metal market dynamics required by the growing clean energy sectors.