Energy dispersive X-ray fluorescence analysis of samples of the Nigerian Zircons

Energy dispersive X-ray fluorescence technique has been applied to determine the elemental composition of natural zircons obtained from Jos plateau, Nigeria. The zircon samples analysed are of the gem variety with very attractive colour mix. As-received crystals were qualitatively analysed in the bulk/solid form while quantitative analysis was carried out using pellets made from pulverised and properly homogenised samples. In addition to zirconium which is the major element with concentrations in the range of 24-26 wt.%, our quantitative analysis showed the presence in minor and trace quantities of 21 other elements/impurities including K, Ca, Mn, Fe, Se, V, Cr, Co, Ni and Rb. In contrast, a number of other elements such as Th and U were observed only in as-received bulk/solid samples, which probably indicates that they are present as inclusions. Scanning electron microscope equipped with EDS analysis confirmed that the major elements present in the samples are zirconium, titanium and oxygen leading to 99.25% ZrSiO4. The obvious distinction in coloration of the zircon crystals is attributed to the difference in concentrations of some of the impurities the material contained. It is conjectured here also that the internal radioactivity of Nigerian zircon could be due to the presence of U and Th impurities.