Geochemical, mineralogical, and geological investigation of potential gemstone occurrences with special emphasis on emerald mineralization in Saba Boru locality, Oromia region, Southern Ethiopia

The present study area is located in Saba Boru locality, Oromia Region, Southern Ethiopia. The study presents geological, geochemical, and mineralogical data collected from stream sediments and major rock types, with whole-rock samples analyzed through laboratory techniques. The geological relationships of the area show the presence of numerous economically viable minerals, including emerald, beryl, tourmaline, and other rare metals such as Tantalum, Niobium, and Titanium. Laboratory results from the study area indicate that emerald mineralization is dominantly influenced by V/Cr trace elements, formed during the metasomatism or hydrothermal processes of granitic pegmatite with mafic-ultramafic rocks interaction. This interaction also led to enrichment in trace elements such as Sr, Rb, V, U, Mo, Th, Fe, Mg, Na, K, Mn, and Ce. Emerald mineralization in the study area is mainly hosted within phlogopite schist rocks, which are associated with basic-ultrabasic volcano-sedimentary rocks such as serpentinite, talc-tremolite schist, and talc schist, all of which were metamorphosed in the Neo-Proterozoic basement of the Kenticha belt. The lithological units in the study area include talc-tremolite schist, talc schist, serpentinite, quartz vein, granitic pegmatite, muscovite-quartz schist, quartz-hornblende schist, muscovite-plagioclase-quartz schist, muscovite-plagioclase schist, and tremolite-muscovite schist. Structurally, the rocks are predominantly oriented in NNE and N-S strike directions. The main objective of this study is to investigate the geology, geochemistry, and mineralogy of gemstone potential, with special emphasis on emerald mineralization. The methodology employed includes field observations, geochemical analysis, and mineralogical analysis. A total of 19 samples from stream sediments and whole rock units were collected and analyzed for trace, minor, and major elements. Among the trace elements, V and Cr were considered as the main chromophores for emerald formation. Other trace elements, such as Fe+ 3 and Mn+2, are also inferred to indicate the formation of blue aquamarine and morganite, respectively, due to their high trace element concentrations in the sample analyzed from the area.