Rare-Earth Elements in Dictyonema Shales of the Baltic Sedimentary Paleobasin

The results of a study of rare-earth metals in dictyonema shales of the Paleozoic Baltic sedimentary basin are presented. In the territory of the studied Kaibolovo–Gostilitsy prospecting area, high up to potentially industrial rare-earth element (REE) contents were confirmed based on a large factual and analytical material. The average REE concentration was 289 g/t with maximums up to 724 g/t. REEs were found in dictyonema shales in various forms (mineral, organic, ionic, molecular, and colloidal). The occurrence of REEs in the mineral matter of dictyonema shales predominated. The fraction of heavy (and most valuable) lanthanides (15.6