Mineralogical and Structural Analyses of Natural Fluorite from Yantuwaru Mining Site, Nigeria

Abstract

Experimental studies of natural fluorite have been reported. In this study, combined X-Ray Fluorescence, FTIR and UV-Vis analyses were performed to give mineralogical information about natural fluorspar. The X-ray diffraction technique was also used to determine the crystallographic parameters and structure of the mineral. Results show a variation of Ca contents and low concentration of F, through all fluorite samples due to Ba and Br contents in the samples, causing replacements of impurity ions in the fluorite lattice. REEs in the fluorite samples were to be found responsible for colour. UV-Visible absorption results showed peaks between 209 to 368 nm, which did not affect the fluorite colour. The 224 nm and 365 nm peaks were caused by the electrons and holes trapped in the Ca2+ interstitial and vacancy, respectively. The absorption bands in the visible range relate to the corresponding fluorite samples. The FTIR results showed absorptions causing CO2 and CO32-stretching vibration due to the CaCO3 and OH stretching vibration due to water in the samples. The structural configuration, the lattice parameters, and the planes confirmed a cubic structure. Obtained results confirmed them to be Calcium Fluorite, as expected.