Occurrence, mineralogical composition and significance of laterites in Kenya
The study area is Kenya a country in Eastern Africa bordered by Ethiopia to the north, Somalia to the east, Tanzania to the south, Uganda to the west, and Sudan to the north-west, with the Indian Ocean running along the southeast border. It is bounded by latitudes 4OS’ and 4ON’ and longitudes 34OE’ and 42OE with an area of 582,646 km². In Kenya Laterites distribution and occurrence has not been studied in detailed. However, studies on soil types in the country have shown that Lateritic soils that occur are of three types. a) Nitisols, the type common especially in the tropical highlands and volcanic steep slopes like Mt. Kenya. b) Ferralsols which occur on gently undulating to undulating topography like in Tsavo. They are very old, highly weathered and leached soils that are rich in Aluminium (Al) and Iron (Fe). c) Acrisols type which occur in the coffee zones in the sub-humid areas, on undulating to hilly topography like Thika area. Where deposits have been found they have found use in surfacing of most roads in the country and in making of bricks for building construction. However, from research study, it has been found that Laterites is an important mineral resource that can be used in defluoridation of ground water with high fluoride concentrations especially, the Rift Valley. An experiment done showed that in 24 hours the fluoride concentration was reduced from 15 Mg/L to about 1 Mg/L in soil samples including Lateritic soils. It has also been found that supergene enrichment in Laterites show traces of Ni, Cr, and Cu that can form ore deposits. Apart from supergene enrichment, Laterites which occurs in association with mafics and ultramafics like serpentinites, dunites, Komatiites rocks and in ophiolite suites may hold ore deposits of mainly Fe, Ni, Co (±Cu) which can be mined commercially in any suitable geological terrane. A good example is the New Caledonia deposit in Australia where nickel occurs in highly serpentinized ultrabasic Lateritic rocks.