Abstract:

Strategic coal-associated mineral resources hold significant importance for national economic development and security. These minerals, often referred to as coal-type minerals, include not only coal seams enriched with critical metals but also partings, coal seam roofs and floors, other enriched layers within coal measures that do not contain coal seams, and even acid mine waters from coal mines enriched with metals. Based on a systematic review of domestic and international literature on coal-type minerals, this paper organizes and analyzes strategic coal-type mineral resources throughout China’s geological history, listing the main periods during which coal-type strategic minerals were formed. It compiles maps showing the spatial distribution of coal mining resources and strategic key minerals during major geological periods nationwide. Using gallium and germanium as examples, the study dissects typical deposits, delving into the geological background and ore-forming mechanisms of coal-type deposits represented by gallium and germanium, and summarizes key prospecting information such as the enrichment sites of gallium and germanium within these deposits. The results show that during various geological periods, strategic critical metal resources, represented by gallium, germanium, and other “four scarcities” and bulk minerals, are the main products. Since the Phanerozoic Eon, “four scarcities” minerals and bulk minerals have been produced. Gallium and germanium deposits in China are mainly concentrated in coal-bearing basins of the North China Platform and Yangtze Platform during the Carboniferous-Permian, Triassic-Jurassic, Early Cretaceous, and Neogene periods. The formation of coal-type germanium deposits is closely related to magmatic activity and associated hydrothermal processes. The enrichment of elements such as gallium and germanium has specific locations within coal-bearing strata: gallium is typically found at the top of coal-forming cycles, such as in the Ga-enriched No.6 coal seam of the Shanxi Formation in the Carboniferous-Permian coal-bearing basin of North China, exemplified by the Heidaigou deposit. The Benxi Formation at the base of the coal cycle also contributes to some extent. Germanium, on the other hand, is usually enriched at the beginning or base of coal cycles, as seen in the Bangmai germanium deposit in Lincang. The gallium and germanium resources in China’s coal have great potential.

Key words: coal-type strategic minerals, forming periods, gallium and germanium, enrichment site, resources potential