Mineralogical and Physico-Chemical Characterization of Clayey Materials of Meka'a (West Cameroon) Preliminary Step for Their Utilization for Human Ingestion

Discovery of new geophagic clayey deposit in the locality of Meka'a contributed to the apparition of new species of geophagic clay materials in the local market. Due to the fact that positive or negative effects of geophagia are conditioned by physico-chemical, mineralogical and geochemical properties of the clay soil ingested, it is therefore necessary to mineralogically and physico-chemically characterize these clayey materials in order to ascertain their health implications. X ray diffractometry (XRD), X ray fluorescence (XRF), particles size distribution, pH and cation exchance capacity (CEC) are the main analyses carried out with these materials. The results show that the clayey materials of Meka’a are extremely weathered and maybe as a result of the weathering of ignimbritic flows. Two main species (yellow and red) of this clay soil are identified on the basis of their colour, mineralogy and physico-chemical characteristic. Analysis of samples of these two types of materials shows that Meka’a clayey materials are mainly made up of kaolinite (64-87%) and goethite (6-25%). These two minerals greatly influence the properties of these materials. Abundance of kaolinite in this clayey mineral assemblage could be of benefit in the protection of gastro intestinal tract resulting from ingestion of soils with high clay content. These clayey soils have a lower CEC and cannot cause cations deficiency in the digestive tract. Their acidic pH makes them suitable for use as remedy for relief of nausea and to curb salivation associated with pregnancy. No dental enamel or gastro-intestinal tract damage was to be feared when ingesting Meka’a clayey soils and their great abundance in Zn could be of benefit to geophagic individuals. However, possibility of Fe supplementation of the clayey soils of Meka’a may be very low considering low ferric hydroxide content and the fact that only a part of Fe present in the clayey soil can be released in the digestive tract.