Introduction to Mining Opportunities
Although the Republic of Equatorial Guinea has become known as a petroleum producer, the full mineral potential of the country is not widely known.
The Ministry of Mines and Energy of The Republic of Equatorial Guinea is seeking to promote various opportunities for mineral exploration in the country; this information serves as a brief introduction to the mineral sector.
The Republic of Equatorial Guinea presents opportunities for gold, bauxite, tantalite-columbite, diamond and base metal exploration in a framework of an established investment code and mining law.
Mining Legislation
The current Mining Law is regulated by decree 9/1981, dated 12th June 1981, which can be summarised as follows:
All mineral resources are the property of the State. The State may exploit such resources directly or by means of a Contract of Participation in Production, with National or foreign companies. Decree 9/1981 regulates precious metals, ornamental stone and metallic and industrial minerals. Aggregates, ballast, radioactive minerals are regulated by separate decrees.
Exploration Concession Areas are awarded for a maximum area of 150,000 hectares and for an initial period of three years, with two possible extensions of one year each.
25% of the exploration are must be relinquished after year two, a further 25% after year three and 75% of the original area must be relinquished by the end of year five.
The Contracts of Participation in Production are at present limited to a term of twenty-five years. If the State elects to participate, it shall fund its participation out of tax entitlements arising from the operation. The State has the right to purchase products in quantities negotiated in the Contract of Participation in Production. The surplus is available for export.
All materials, machinery, equipment and replacement parts which are not produced locally may be imported free of all charges. A model contract is available, but the terms of each Contract of Participation in Production are negotiable, and the model contract is currently under review.
Production is currently subject to a 5% royalty, and tax on profit is levied at 20% until the initial investment is recovered, after which the tax on profit is 50%.
The royalty and tax regimes are currently under review.
Geology
As the islands are mainly Tertiary volcanics with little mineral potential, the discussion which follows refers to the mainland enclave of Rio Muni. The geology of Rio Muni falls into four main divisions:
- Archaean granite terrance, which occupies all the central and east, and parts of the southwest of the country.
- A northwards widening wedge-shaped gneiss belt, of probable early Proterozoicage, which extends from near Congo in the southwest to the vicinity of Micomiseng and Rio Ntem in the north.
- A small area of metasediments of probable late Proterozoic age around the Muni estuary. Rio Mitong and Rio Mandyani in the southwest of the country.
- A coastal strip of Cretaceous to Recent sediments.
The Archaean granite terrain is generally correlated with the Ntem complex of Cameroun. It comprises granite, quartz diorite with zones of banded iron formation, granite gneiss and intrusions of norite, gabbro, diabase and pegmatite. Much of the granite contains amphibole or is charnockitic. Zones of quartz diorite, basic rocks and gneissic fabric show a NE-striking grain, which is parallel to foliation in the adjoining gneiss belt and, together with the charnockites suggests a tectonothermal overprint. Some post-tectonic gabbros and diabase bodies in the south-east of Rio Muni are aligned NW-SE and extend into the Mitzic area of Gabon.
The gneiss belt comprises predominantly garnet gneisses in the north, amphibole gneisses in the west and south and widely developed pyroxene gneisses. The gneisses include zones of granite gneiss, quartz-diorite, pyroxene-diorite and magnetite- quartzites. Ultrabasic and syenitic bodies were emplaced along major faults near Niefang. The development of the gneisses may be broadly correlated with the Eburnean tectonothermal event, dated at 2000 my, and which possible overprints the Archean granite terrane, resulting in the formation of charnockites.
The metasediments in the southwest of the country are predominantly red arkoses and argillites, but a black bituminous shale is developed locally. These rocks are thought to be part of the West Congolian Belt. They are therefore broadly contemporaneous with the Pan African tectonothermal event, with an age in the range 500-700 my, and are therefore probable analogues of the copper-rich Katangan of Zaire and Zambia.
The Cretaceous to Recent sediments of the coastal strip were deposited in a fault-controlled linear graben associated with the opening of proto-Atlantic. The sequence begins with a thick polymictic conglomerate, which is overlain first by lacustrine and then by marine facies sandstones, siltstones and shales. All lithologies contain abundant bituminous material derived from plant residues. The sequence contains numerous intraformational breccias and slumps which are consistent with repeated movements on the boundary faults. At any time horizon, the facies become more marine and lithologies become finer when traced southwards.
Comparison with the geology and mineralisation of Cameroun and Gabon suggest that the Archaen granite terrain is prospective for gold, diamonds and for rare-earth and tin-bearing pegmatites. The Proterozoic gneiss terrain might be prospective for iron ore in the banded iron formations and gold and possibly nickel associated with ultrabasics emplaced in the fault zone near Niefang, which may represent a suture zone. The late Proterozoic could be prospective for base metals, cobalt, nickel, uranium and gold. Lateritic terrain may be prospective for bauxite and possibly lateritic nickel-cobalt deposits.
Exploration History
Sporadic investigation prior to 1975 noted the major geological divisions and highlighted potential for oil, gold, base metals, bauxite and pegmatite minerals such as tin, tungsten and tantalite-columbite. Few useful records remain from this time.
In 1975, geologists of the former Soviet Union completed a preliminary assessment of gold, tantalite columbite, iron ore, bauxite and radioactive minerals.
Between 1980 and 1986, BRMG undertook regional and follow-upstream sediment heavy mineral and geochemical exploration for gold, tantalite-columbite, diamonds, iron ore, radioactive minerals, rare earths and base metals.
G.E.M.S.A. in the years 1981-1983, initiated exploration and evaluation of gold, iron ore, ornamental stone, molybdenite, tantalite-columbite, bauxite and diamond opportunities. G.E.M.S.A. also undertook airborne magnetic surveys and constructed SLAR mosaic of the country at 1:400,000.
Assessment of Exploration Results
As a general statement, exploration in Equatorial Guinea has suffered from a lack of continuity and a repetition of early stage work by the involvement of several foreign geological survey organisations. Climatic and topographical conditions and poorly developed infrastructure caused operational difficulties for each of these organisations. In particular the thick rain forest and the lack of detailed topographical maps severely inhibited operations. Few of the investigations progressed beyond the reconnaissance stage before the activity of each organisation was curtailed. The reconnaissance stage is, however, well-covered from the aspect of stream-sediment heavy mineral and geochemical sampling.
The new follow-up operations which were conducted, ie. gold at Coro and tantalite-columbite at Aconibe, both involving eluvial / alluvial sampling, suffered from a lack of size analysis of the mineral grains and consequently the wrong choice of sampling technique. Samples were generally far too small, by several orders of magnitude, to be meaningful. No bedrock prospect has been drilled. Promising indications are as follows: –
Gold
There are widespread indications of gold in granite and gneiss terrain with favorable Archaean and Proterozoic ages. Indications of a late or post Eburnean hydrothermal mineralisation were recently recognised in gneisses beneath eluvial gold deposits and gold flakes are present in bedrock. Coarse filigree gold flakes, which have not been mechanically transported, occur in surficial deposits, with grades ranging between 0.5/cubic metres and 4g/cubic metres.
Bauxite
Widespread lateritisation, and indications of high A1203, low Si02 bauxitic laterite with grades to 58.3% A1203, and Si02 in the range 2.1% to 5.3%, support the potential for Bauxite particularly in the Nzanagavong and Akoakan areas.
Tantalite-Columbite
Discrete but laterally extensive (152 km2) occurrences of pegmatite, with strong indications of tantalite-columbite mineralisation, including average grades of 3.0-7.5 kg/cubic metre in overlying eluvial and alluvial deposits, occur in the Acocsang area.
Diamonds
Structural lineaments containing basic instrusives extend along strike from the Mitzic diamond occurrence in Gabon, into the Nsork area. Heavy mineral sampling results are negative, except for zinc-rick chromites, found near Nsork. At Mitzic, such sinc-rich chromites are only found in close proximity to diamonds.
Base Metals
Anomalous U, Ni, Co, Pb, Zn, Cu, As, Ag and Mo values were detected in laterite above black shale which occurs at the top of the red-bed sequence near Congo. The red-bed sequence is part of the West Congolian and equivalent to the Katangan sequences of Zaire and Zambia.
Data Available
Soviet Union Geological Survey 1974-1975
Report: Informe Sobre Los Trabajos Del Equipo de Expertos Geologos Societicos En La Republica De Guinea Ecuatorial.
Bauxite: 70 samples Gold: 24 pit samples Columbite-Tantalite: 8 pit samples
GEMSA 1980-1982
Reports:
Informe Sobre Posibilidades de Recursos Minerales En la Republica De Guinea Ecuatorial. March 1980.
Prospeccion Geofisica Aerotransportada En Guinea Ecuatorial. March 1981
Radar orientado lateralments SLAR Para El Estudio De Recursos Naturales e Imagenes Landsat aplicadas al Mismo fin. March 1981.
Trabajos de infrastructura Geologico-Mineras en el territorio Continental de Guinea Ecuatorial. Mayo 1982 en 6 volumes.
Proyecto Para la Investigacion Y Evaluacion de Las Areas Seleccionadas. en el territorio Continental de Guinea Ecuatorial. Julio 1982.
Airborne Magnetic and Radiometric Survey 16,118 line Km Heavy Mineral Concentrates 2,802 samples Stream Sediment Geochemistry 2,438 samples Soil 3,228 samples Rock 362 samples
BRMG 1980-1985
Reports:
Prospeccion Sistematica En Guinea Ecuatorial :
Primera Fase 81 RDM 016 AF 1981
Segunda Fase 81 RDM 016 AF 1981
Tercera Fase 83 RDM 059 AF 1983
Cuarta Fase 85 GNQ 051 1985Heavy Mineral Concentrates 841 samples Stream Sediment Geochemistry 3541 samples Diamond Indicator Concentrates 21 samples Soil samples 629 samples Pits samples 57 samples Banka Drill Holes 66 samples Petrographic Samples 1265 samples
Further information
Further information on data availability or any other matters concerning exploration opportunities in Equatorial Guinea can be obtained from: –
Ministerio de Minas y Energia
Malabo, C/12 de Octubre S/N
Republic of Equatorial Guinea
Phone: +240-9-3567
Fax: +240-9-3353
Telex: GBNOM 5405 EG
Mr Crisobel Mariana Ela’ Secretary, General Ministry of Mines and Energy (Direct Phone: +240-9-3405)
The industry is regulated by the Government’s Ministry of Mines and Hydrocarbons which is located at Malabo. The current Minister of Mines and Energy is Mr Juan Olo Mba Nseng while Mr Miguel Abia Biteo Boriko is the Director General of Mines and Hydrocarbons. The postal address of the Department of Mines and Hydrocarbons is: P O Box 778, Malabo, Republic of Equatorial Guinea.
