Geochemistry, mineralogy and genesis of rare metal (Nb-Ta-Zr-Hf-Y-REE-Ga) coals of the seam XI in the south of Kuznetsk Basin, Russia

The research describes the detailed mineralogical and geochemical characteristics of rare-metal Nb-Ta-Zr-Hf-Y-REE-Ga ores found in Permian coals in the layer XI in the south of the Kuznetsk Basin. The concentrations and distribution of ore, and related elements, were studied in the coal seam section and along the seam strike. Spatial and genetic relationships of the mineralization in the coal were found to be related to the presence of an altered volcanogenic pyroclastic horizon of REE-enriched pantellerite composition. The highest concentrations of basic ore elements in the coal are associated with the contact zones above and below the volcanogenic horizon. The ore matter is mainly concentrated in the fine mineral phases, composed mainly of Zr-Nb-Ti-Fe oxides, fine zircons, rare-earth carbonates (bastnesite) and phosphates (monazite, xenotime, goyacite). Resource estimates are made of the rare metals. Confirmation of the connection between the complex rare-metal mineralization and the alkaline volcanogenic pyroclastics significantly expands the prospects of revealing further such mineralization in the coals of East and Central Asia.