Mineral and Rock Profiles
Bauxite: Gondama Deposit
The Gondama Bauxite Deposit in Sierra Leone’s Moyamba District managed bySierra Minerals Holdings 1 Limited (VIMETCO) is a key source of high-grade bauxite, essential for aluminum production. The deposit contains approximately 31 million tonnes of bauxite, with a grade of 46% alumina (Al O ), 3.0% silica (SiO ) with an annual production rate of about 2 million tonnes.
Chromite: Hanga Deposit
The Hanga Chromite Deposit in Sierra Leone’s Kenema District is a historically significant source of chromite, previously mined by United African Co. Limited between 1937 and 1962. The deposit, located within the Kambui Greenstone Belt, features high-grade chromite ore with a Cr2O3 content of 38-44%. Chromite is essential for producing chromium, used in stainless steel, chrome plating, and alloying.
Columbite-Tantalite (COLTAN) Ore
The Columbite-Tantalite (COLTAN) Ore Deposit in Sierra Leone’s Kono District is a notable source of critical minerals, including columbite and tantalite, which are essential for producing tantalum and niobium. These metals are vital in high-tech industries, particularly for electronic components and alloy production. Geologically, the deposit is part of the Archaean Basement rocks, hosted within biotite granite and porphyroblastic granite formations, indicating its mineral wealth.
Hematite (DSO): Farangbaya Deposit
The Farangbaya Hematite Deposit is a significant contributor to Sierra Leone’s mining sector, offering a high-quality iron ore resource. Its geological formation and extensive reserves make it an essential resource for the global steel industry.
Ilmenite Concentrate: Gbangbama Deposit
The Gbangbama Ilmenite Deposit in Sierra Leone’s Bonthe District is also mined by Sierra Rutile Limited as a by-product of rutile mining. The ilmenite, derived from quartzo-feldspathic gneisses of the Precambrian Kasila Group and hosted in Bullum sediments, ranges in quality from 15% to
26%. Ilmenite is a key ore in the production of titanium dioxide (TiO ), used in paints, plastics, paper, welding rods, and various industrial applications.
Irone ore Concentrate: Lunsar Deposit
The Marampa Iron Ore Deposit, located in Sierra Leone’s Port Loko District, is a major Iron Ore asset with an estimated resource volume exceeding 1 Billion tonnes. Mined by Marampa Mines Limited, the deposit features high-quality iron ore with a grade of 65% Fe, making it highly desirable for global steel production. The deposit plays a key role in Sierra Leone’s mining sector, boosting local economies and attracting international interest.
Lithium Ore: Kalangba Deposit
Good indications for Lithium are mainly in the Greenstone belts of Sierra Leone (Kambui Hills, Kangari Hills, Sula Mountains, and Gola Forest)
The Kalangba Lithium Ore Deposit in Sierra Leone’s Kanji Hills, managed by Leone Afric Metals Limited is a significant lithium resource, primarily containing spodumene and lepidolites, lithium-rich minerals found in granitic pegmatites.
Industrial Grade Rutile Concentrate: Gbangbama Deposit
The Gbangbama Rutile Deposit in Sierra Leone’s Bonthe District, operated by Sierra Rutile Limited, is a major source of industrial-grade rutile concentrate, a high-quality titanium mineral and the world’s largest natural rutile deposit. Geologically derived from quartzo-feldspathic gneisses of the Precambrian Kasila group and hosted within Bullom sediments, it is estimated to contain 867 million tonnes of rutile, with 95% TiO2 purity. This makes it highly valuable for
applications like pigments, welding electrodes, and titanium metal production.
Tin Ore: Kamakwei Deposit
The Kamakwei Cassiterite Mineralization in Sierra Leone’s Karene District is a notable source of cassiterite, the primary ore of tin. Located within the Loko Hills Greenstone Belt, it features formations of amphibolite, quartzite, and banded ironstone. Concentrate has an estimated tin grade of around
40%, indicating moderate concentrations of tin.
Zircon: Gbangbama Deposit
Sierra Rutile Limited mines the Gbangbama Zircon Deposit, a by-product of rutile mining, in the Bonthe District of Sierra Leone. The zircon is found in the Bullum deposits and is produced from quartzo-feldspathic gneisses of the Precambrian Kasila Group. About 15% of the heavy mineral
sands in the deposit are zircon. Industrial applications for zircon include the production of ceramics, abrasives, refractory materials, foundry mould coatings, and nuclear reactor building.
Rock Sample: Chromite
The specimen is a black, highly dense, and massive olivine chromitite, haracterized by its weak magnetic properties. The primary mineral composition includes olivine and chromite, giving the rock its dense structure and dark coloration. The weak magnetism suggests a relatively low iron content within the olivine and chromite phases. This type of chromitite is typically associated with ultramafic rock formations and is
an indicator of magmatic processes.
Rock Sample: Hematite Schist
The specimen is a black, highly dense, and massive olivine chromitite, haracterized by its weak magnetic properties. The primary mineral composition includes olivine and chromite, giving the rock its dense structure and dark coloration. The weak magnetism suggests a relatively low iron content within the olivine and chromite phases. This type of chromitite is typically associated with ultramafic rock formations and is
an indicator of magmatic processes.
Rock Sample: Kimberlite
The specimen is a very dark (black), dense, coarse-grained porphyritic kimberlite. It is primarily characterized by 7-10mm pyroxene phenocrysts embedded within a finer-grained matrix. The distinct contrast between the large pyroxene crystals and the finer surrounding matrix highlights the
porphyritic texture of the rock, typical of kimberlites.
