Liberia is a small country of about 110,000 km2. Geologically, it makes up part of the Archaean age craton called the Man Craton (also called the Leo Shield). It is also well known as having a number of large iron ore deposits, several of which have been mined in the past, and abundant occurrences of gold and diamonds.
In fact, it is the western two thirds of the country which forms part of the Archaean Man Craton, being formed of a series of medium to high grade metamorphic rocks (up to granulite facies in places). The main rock types, as identified on the USGS geology maps which were compiled in the 1970s, are a variety of gneisses, including granitic, granodioritic, quartz dioritic, leucocratic and melanocratic types. This metamorphic terminology rather obscures the fact that the craton is made up of essentially metamorphosed granite / greenstone terrain. As such, the cratonic area has high potential for greenstone hosted gold deposits (an example are the Weaju and King George Larjor [KGL] deposits of Afferro Mining Inc). Like many Archaean cratonic areas of the world, the Man Craton also contains good potential for diamond deposits, as exemplified by the Kono diamond field in eastern Sierra Leone, regarded by many as the most prolific alluvial diamond field in the world.
The boundary between the Archean and Birimian provinces is not well defined but moving into the Eastern third of Liberia, the surface and exposed geology is no longer Archean but is made up of Birimian age geological sequences. On the USGS maps, mentioned above, the main rock types in the east of Liberia are shown as being broadly the same as those in the west (ie. dominated by a series of different gneissic rocks), though with minor schists as well. It appears that this designation as Birimian is well established and this means that the area should share the high gold potential of the rest of the Birimian sequences in West Africa. In effect, the Birimian of eastern Liberia forms the south western extremity of the Birimian of West Africa. There are numerous examples of major gold deposits in the West African Birimian, including Ashanti, Prestea and Bibiani in Ghana, Yaoure and Ity in Ivory Coast, and Sadiola, Loulo, Morila and Syama in Mali. All these deposits are, or have been, multi-million ounce gold mines, and there are large numbers of medium and small deposits as well.
This area of the Birimian which covers eastern Liberia is the only unexplored section of this geological domain, and Hummingbird Resources is the predominant explorer of this region.