Multi Spectroscopic Techniques to Analyze Natural Minerals to Determine Corundum Type of Gemstones from Darfur, Sudan

Abstract

The main objectives of this study were to know natural minerals contents to classify their types and determine corundum type. Energy Dispersive X-ray Fluorescence spectrometry, X-ray diffraction and Energy Dispersive X-ray Spectrometry coupling with Scanning Electron Microscope have been utilized to determine the mineralogical and elemental composition of semi gemstone samples collected from two different mine locations in Darfur region western Sudan. Results obtained from spectroscopic analyses indicated that Aluminum Oxide (Al2O3) was predominated in FDY sample(A) and Silica (SiO2) was main contain in ODS sample(B) as well as different percentages of some metal oxides including trace and rare earth elements. According to the outcome of the Energy Dispersive X-ray Fluorescence results the FDY sample is characterized as Corundum (Ruby) and while the ODS sample is classified as Quartz (Carnelian). These characterizations are depended on physical appearance and color that when compared to the previous data of gemstones in addition to the analyzing results .The analysis showed that ruby major revealed composition were Al2O3 (79.02 %); SiO2 (10.88%); SO3(4.96%) Fe2O3 (2.27%); CaO (1.06%); TiO2(1.08%) and quartz majority compositions were SiO2 (94.23%) ; Al2O3 (1.96%); SO3 (0.66%) Fe2O3 (2.10%); CaO (1.05%); TiO2 (0.03%). X-ray Diffraction scanning tests of the samples showed that a vast majority represented by corundum (93.3%)and quartz (99.1%) in FDY and ODS samples respectively as dominant compound ,similarly for more investigation and delicacy Energy Dispersive X-ray Spectrometry coupling with Scanning Electron Microscope scan analyzing indicated that Al compounds(Al2O3) were outnumbered Si compound(SiO2) in FDY sample while in ODS sample there was a significant presence of Si contents represented by standard level (SiO2) on the bases of available facts of the study FDY sample considered to be corundum (ruby) and ODS sample as quartz origin.