Case study of fluorite mineralization using traditional and laser spectroscopic techniques, homret akarem area south eastern desert, Egypt

Abstract

Green fluorite samples from Homret Akarem, eastern desert Egypt, were investigated by laser-based Raman spectroscopy to study the effect of rare earth elements (REEs) and natural radiation from the surrounding environment on their physico-chemical properties, taking into consideration the geological setting. Geochemical data of trace elements display fluorite enrichment with Y, Pb, Sr, Sn, and other REEs. XRD showed lattice parameters with values higher than those for synthetic fluorite due to the substitution of Ca by Sr and less likely by radiation from U. A considerable shift in the binding energy (BE) for Ca and F obtained from the XPS spectrum indicates that U carried by the hydrothermal solutions formed a discontinuous thin film on the surface of fluorite. Laser-Raman spectroscopy showed strong peaks below 500 cm⁻¹ and both shallow and weak peaks above 500 cm⁻¹. The strong peaks indicate that the substitution of Ca by Sr, point defects, and natural radiation caused by U have a stronger effect on the crystal structure than REEs. Raman spectroscopy supported the initial reports of uranium minerals like Rutherfordine, Kasolite, Soddyite, and Uranophane-alpha.