From this time the mineral industry started substantial contributions to the Liberian economy.
The geologic setting seems favorable for the formation of the following geology types of deposits:
(A) Precambrian chemical sedimentary, banded iron and manganese formations, also submarine exhalative processes bordering with the continental nucleus e.g. iron, manganese, phosphate.
(B) Archeane grindstone and metasedimentary belts with granite associations, e. g. gold and sulfide deposits.
(C) Residual concentration, e. g. bauxite
(D) Mechanical concentration of steam and beaches placers, e.g. diamonds, gold, heavy mineral brach sand etc.
(E) Magnetic concentration, e. g. Diamond pipes and dykes;
(F) Hidrothermal processes e.g. gold, barite.
Present mineral production in Liberia involves iron ore, diamond and gold mining which together contribute more than 65 percent of the value of the total export earnings of the country. Mining, therefore, dominates the monetary sector of the economy and represents the most important economic activity. The overal contribution of the mining sector to Gross Domestic Product at constant factor cost showed an average of 30 percent in 1980 and 1981, after averaging 25 percent per year from 1977 to 1979. The mining industry also provides a means of livelihood to a large number of workers and their dependants. Total number of workers in mining and quarrying stand at 20,000 in 1981 which represents about 3 percent of the working population. Mining operations have also led to the provision of infrastructural facilities such as hospitals, schools, electricity, water supply etc. in those areas where the mines located (mining communities). The availability of the structures, which under normal circumstances those areas would not have benefited from has therefore enhanced productive capacity of those areas. The sector has also been a source of revenue payments such as royalty, profit sharing, export duties, income tax, exploration licenses, minings licenses, brokers and dealers licenses to the goverment.
Iron ore mining has constituted the most important activity since 1965 and is now carried out by three companies (LAMCI, BMC and NIOC) since the closure of LMC in 1977; the companies altogether produce over 20 million long tons of crude ore per year, which makes Liberia the leading exporting country of iron ore in Africa, and ranks seventh in the worth. Production, however, might fall this year due to the world wide problems facing the iron ore industry.
Other mining activities, mainly for placer gold and diamonds, are done on a small scale by hand-methods with the exception of one mechanized gold mine once operated near Zwedru (BITC) in Grand Gedeh County; the production of gold and diamonds can only be measured in terms of export volume.
The production of gold increased by 121 percent from 7,243 ozs in 1980 to 15,991 ozs in 1981. Diamonds production also showed an increase of 5.2 percent, but suffered a sharp fall in value by 30 percent caused by a 50 percent drop and low demand on world market.
Despite such previous and present mining activities, vast mineral wealth still remains untapped in the country. Iron ore reserves of both proven and problem nature total over 4 billion long tons of crude ore.
Apart from her minerable reserves of iron ore, diamonds and gold, Liberia also has important potential of reserves of barite, kyanite, phosphate, heavy mineral beach sands, bauxite, manganese, tim, chromiun and base-metals, sulfides. The rest of the text describing the mineral resources of Liberia has been prepared to include the historical background and the production of the principal mineral deposits of the country.
Exploration activities of the Geologic Survey and the private organizations have shown that all of the known economic gold deposits occur as alluvial deposits, along valley bottoms and in stream. The deposits are widely distributed over a total area of 10,000 square miles throughout the country, but are much more concentrated in Eastern and Western Liberia.
The distribution pattern of the gold in the buried/active stream sediments shows some relationship with the north-east-trending, Precambrian schists/greenstone belts with and the underlying basement complex of Liberia and “Eburnean Ages”, and it is belived that these deposits are derived from the prolonged weathering from Pleistocene to recent times of small lenticular quartz veins (lode deposit) associated with these archeane rocks.
Gold was found in lode deposits in the Tawalate District, at Wueju, east of Gondoja, near Zwedru and at Gbarmu, which occur as quartz veins. Most of these veins are narrow and very reach such as in the Zwedru area, which was only about 3 feet thick and assayed about 892 gm/tonne Au.
Reserves and Potential
It seems probable that many more placer deposits will be found in many part as the Tiehnpo and Kpo Range gold belts and Zoi area which can be worked profitably whith adeguate pumps and a simple other mechanical equipment.
There is ample evidence that Liberia has sufficient gold ore; roughly estimated to be greater than 1 million troy ozs.; planned exploration is used to test the many areas delineated, including the old prospects.
At the present time, practically 90% of the world’s gold mines are situated in areas of Precambrian rocks (shield areas) such as those of Liberia which are relatively favourable for the development of gold mines and for the persistence of the gold in depth. The recovery of certain associated minerals, occurring whith the gold, contain metals of strategic importance, will no do doubt increase the economic value of some of the law-grade placer deposits.
Though diamonds were discovered in the 1930’s in western Liberia by the Holland Syndacate, it was not until the early 1950’s that diamond digging started in Liberia. Digging started along the Lofa River near Wuesua and gradually spread downstream and to adjoining tributaries. The Kakata area was also mined in the early 1950’ and from by the late 1950’ digging had started at Gbapa and Bahn where there was a considerable rush. Minning by thousands of diggers extended in early 1960’s to the Kumgbor areas. During the early 1960’s attempts were made to form companies to mine the river beds and adjoining tareas by mechanized means. The Liberian Swiss Mining Company (LISWIMCO) and Globex Minerals, Inc. were actived in this venture. The most serious large scale exploration was, however, carried out by the Diamond Mining Corporation, Liberia (DCML) from 1962-66. DCLM was responsible for locating a number of Kimberlite dykes in western Liberia which are uneconomic in diamond content. In 1972 the U.N. Mineral Survey Team discovered a small kimberlite pipe whith no diamonds in it. More recently there are about 947 local alluvial diamond mining claims whith over 1000 registered prospectors.
Reserves and Potential
To conclude this section, it must be pointed out that although available records show that over 13 million carats of diamonds have already been produced and exported from Liberia, field investigations indicate that Liberia still has modest reserves of diamonds (over 10 million carats) to last beyond the year 2000.
It is likely from the widespead occurrence of kimberlite indicator minerals in western Liberia, that the alluvial diamonds are derived from as yet undiscovered kimberlite pipes. Suchs pipes have been found in adjoining Sierra Leone and are now being mined.
Further exploration work in Liberia, especially in the Kumgbor areas, to try to discover new and diamondiferous Kimberlite dykes swarms and pipes, is obviously warranted. A road network will be needed to open up the Gola Forest Reserve for such investigations.
About 13 kimberlite dykes generally trending N30 E were located by DCML in western Liberia from 1962 -'66. Some of the dykes are diamandiferous but not in economic quantities, while others perhaps have not been well sampled. On account of the abundance of large crystals of picro-ilmenite, the Kumgbor area holds the best potential for the occurrence of diamondiferous kimberlite pipes.
The Mano-Godua pipe was located by a U.N. mineral survey through a magnetometer survey and drilling in an area of known diamond diggings.