Uranium, which is included in lanthanides series and an element with the highest atomic number of any naturally occuring element, is found in granites, metamorphic rocks, lignite, monazite sands, and phosphate deposits as well as minerals. The concentration in phosphate rocks can be as high as 0.12 mg/g.[1] Currently, uranium is the most important nuclear fuel. Enriched uranium is used as a material of high density in the aeronautics industry, as radiation shielding, as an additive for catalysts or steels, and in the glass and ceramics industries. Some plants, such as olive trees and certain fungi, are able to store uranium contents of several g/kg.[2] Uranium compounds are extremely