RARE-EARTH ELEMENTS IN A SAMPLED COAL FROM THE PIRIN DEPOSIT, BULGARIA

Rare earth elements (La, Ce, Sm, Eu, Tb, Yb, and Lu) in a columnar section of the coal of the Pirin deposit, Bulgaria, have been determined by neutron activation analyses. The REE content in the coals is lower than the average REE content of shales from North America, Europe, and the Soviet Union. The REE abundances increase with the increasing ash content of the coals. The source of REE in coals is mainly the suspended terrigenous material. The specific enrichment in the ash of low-ash coals is a result of the interaction between the dissolved REE and the products of disintegration and decay of organic substances, mainly humic acids.