Geochemical appraisal of major elements in geophagic clays from Vhembe District, South Africa

Geophagic clays are consumed by human beings and other members of the animal kingdom for a number of reasons such as mineral nutrient supplementation, relief of early morning sickness in pregnancy and craving. The objective of this study was to assess major elements in geophagic clays in order to know clays that were enriched or depleted in major elements of nutritional value. The major elements were determined by means of X-ray fluorescence spectrometry (XRFS). The average concentration of SiO2, Al2O3, Fe2O3 and TiO2 are 42.52%, 29.20%, 12.04% and 1.26% respectively with low content of CaO (0.26%). Chemical index of alteration (CIA) values for geophagic clays ranges from 17.09 – 99.07. There are no differences in major oxides of Mg, Mn, K and P in geophagic and non-geophagic clays. Cluster analysis of the major elements showed two groups of chemical differences amongst the elements in geophagic clays, low and moderate to high degree of weathered clays. Functional analysis showed that some of the geophagic clays were enriched in SiO2, Al2O3 and Fe2O3 and depleted in CaO, K2O and MnO. Geophagic clays devoid of Al2O3, SiO2, MgO and those that are enriched in Fe2O3 and CaO are ideal for human consumption because of the potential benefits that are associated with Fe2O3 and CaO in human metabolism.