Coal-hosted Ge deposits of the Russian Far East

This paper summarizes results from a study of the geology and geochemistry of Ge deposits in the coal-bearing basins of the Russian Far East. The deposits are located at the small rift-controlled coal basins and are characterized by fault control and a dome-like shape. Ge is concentrate in coals (from lignite to subbitiminous in rank) and coaly sediments. The average Ge contents in the coal of the various deposits range from 100 to 1000 ppm. Along with Ge, metalliferous coals accumulate many of trace elements. The contents of W, Mo, U, Ga, Be, Zn, V, B, As, Sb may be as high as hundreds of ppm, Ag, Hg, Tl – up to some ppm and Au –up to hundreds of ppb (on whole coal basis). These deposits may fonn only in an organic-rich sediments due to absorption of Ge by organic matter from ascending Ge-rich solutions. Among these are: (1) acid magmatic fluids; (2) meteoric N₂-rich alkali thermal waters; (3) high PCO₂ waters which are result of mixing of Ge-bearing fluids of the former two types.