Coal-hosted rare metal deposits: Genetic types, modes of occurrence, and utilization evaluation

The study on rare metals in coal and coal-bearing strata is a hot point issue in the field of coal geology. Rare metals that could be highly-enriched in coal and coal-bearing strata and thus can be industrially utilized include Li, Sc, Ti, V, Ga, Ge, Se, Zr, Nb, Hf, Ta, U, rare earth elements (lanthanides and Y), and noble metals. In this paper, the geological origin, modes of occurrence, and evaluation methods for coal-hosted rare metal deposits including Ge, Ga, U, Nb, rare earth element ore deposits are reviewed. The study on coal-hosted rare metal ore deposits can not only provide important evidence of coal geochemistry and coal mineralogy for coal formation origin, coal-seam correlation, coal basin formation and epigenetic deformation, regional geology-evolution, and sudden geological event, but also are practically significant for the development of coal circular economy, environmental protection during coal utilization, and for the security of national rare metal resources.