No abstract

Carbonatite occurrences are reported in Lueshe, Kirumba, Bingo and Mombadio in the Democratic Republic of Congo (DRC), within the western branch of the East African Rift System (EARS). These rocks intrude Precambrian rocks , which are mainly quartzites and mica schists. Lateritic profiles from Lueshe and Bingo are ore-bearing minerals enriched in Nb 2 O 5 and phosphate minerals. The Lueshe and Bingo exploitable quantities are estimated to be 30 Mt at a grade of 1.34% Nb 2 O 5 and 7 Mt at a grade of 2.86% Nb 2 O 5 , respectively. These carbonatites were explored and exploited by some mining companies in the 1970s and 2000s. They show geological and geochemical similarities to other exploitable carbonatites in the EARS, including Mrima Hill in Kenya, Panda Hill in Tanzania and the world-class Araxá and Catalão carbonatites in Brazil. The Lueshe and Kirumba alkaline massifs dates, determined using the whole-rock Rb-Sr method, are respectively 822 ± 120 and 803 ± 22 Ma and are intimately linked to the Rodinia Supercontinent breakup. These dates are analogous to other regional carbonatite dates like the Matongo carbonatite in Burundi. However, further geological, petrological and geochemical studies on carbonatite complexes are essential in DRC. Most importantly, the economic potentials of Kirumba and Mombadio should be evaluated. Simultaneously, the dates of the Bingo and Mombadio carbonatites are crucial for the elucidation of their geodynamic settings.

The Numbi district of eastern Democratic Republic of the Congo (DRC) has high mineral interest; it has been exploited for decades by small scale artisanal miners for rare metals such as Sn, W, Ta and Nb. This area was investigated to elucidate the petrology of the basement rocks and to make their detailed geological map. From the petrographical and geochemical analyses, six lithological units were characterized. Granite and schist were the two main lithologies with some associated smaller rock units such as amphibolite, diorite, quartzite and pegmatite. Biotite is the common mineral found in all lithologies. The granite displays the mineralogical assemblages with the abundance of muscovite, biotite, feldspar, plagioclase and quartz. Diorite and amphibolite display less amount of quartz. Hornblende is very abundant in the amphibolite; less is the schist and a very small amount in the granite. Feldspar is mostly found in the granite, quite found in the quartzite and less in the schist rocks. In adding to these mineral assemblages, accessory and opaque minerals (iron oxide) are in a very small amount. Pegmatite is mostly found as altered veins. Schist, quartzite and granite samples share the fields of granodiorite while diorite and amphibolite samples share the fields of diorite and gabbroic diorite on the total alkali-silicate classification diagram and ranged under intermediate and acidic rocks. The area is abundantly rich in rare metals (pegmatite with Nb-Ta-Sn mineralization) and is fairly suitable for quarry activities.

Rare earth elements (REE) are not as rare as their name indicate, but the deposits in which they are found at an economic interest are not very common. They are enriched in carbonatites, pegmatites, alkaline and per-alkaline igneous rocks, placers, laterites, veins, bauxites and iron adsorption clays. Economic deposits of REE are mined from 3 main minerals, which are bastnaesite, monazite and xenotime. REE have been widely used in many high-tech and green technology gadgets, including batteries, computer memories, permanent magnets, smartphones, solar panels, wind turbines, speakers, air conditioners and many other applications. Due to these applications, REE are sought after by many developed and developing economies. The Democratic Republic of Congo (DRC) is endowed with mineral potentials. Studies have speculated REE concentration in areas with carbonatite complexes such as Lueshe, Bingo and Kirumba. Other regions with REE potentials include pegmatites. A high weathering rate contributes to metals and REE deposition in lateritic profiles of pegmatites and other alkaline rocks. Additionally, there are placers in many locations of riverbanks. For example, the alluvial placers of Kabengelwa, Mashabuto and Obaye are enriched in monazite and contain significant quantities of rare earth oxides. We believe that, with more research and explorations, the DRC could be a potential target for future REE projects.