Natural Radioactive elements, their geological origin, way of appearance and migration

This paper has a comprehensive approach to the problem of natural radioactivity. It explains the behavior of natural radionuclides in geological environments, their crystallochemical and geochemical characteristics and the paths of their liberation from various rocks and mineral during alternation processes. Special attention was dedicated to the uranium enriched granitoids, vulcanogeneous, metamorphous and sediment geological complexes. The list of more, important locations and areas in Serbia, enriched with uranium fixation, with or without change of its oxidation state, during the process of precipitation or adsorption, with explanation of some environmental contamination processes, were discussed in detail. (author)