Geophagic Clayey Materials of Sabga Locality (North West Cameroon): Genesis and Medical Interest

Elvis Duplex Kenne Kalguem

doi:10.11648/j.earth.20190801.14

Abstract

Geophagia, the deliberate ingestion of clayey materials, is a complex eating behaviour with obscure etiology and numerous health/medical problems. Geological, mineralogical and geochemical studies were carried out on Sabga geophagic clayey materials located within a trachyte Bamenda mountain, about 16 km east of Bamenda town (North West Cameroon), in order to define the genesis, and its medical interest. Four (04) samples were characterized by different techniques: description of outcrops and pits, particle size distribution by laser dispersion, X-ray diffraction, Fourier transform infrared spectrometry, Scanning electron microscopy and bulk chemical analyses. The main clay minerals were smectite (49-60%) and kaolinite (4-6%). The other major minerals are quartz (19-34%), feldspar (6-12%), goethite (3-6%), and hematite (1-3%). The average particle diameter varied from 2 to 9 μm. Results from the different analytical techniques point out a meteoric weathering of feldspar as petrogenetic origin of geophagic clayey materials. Smectite and kaolinite, which are the main desirable minerals components of the geophagic clayey materials, were geochemically derived from surrounding trachytes. However the presence of crystalline silica (quartz) up to 2% limits the application of some Sabga geophagic clayey materials for pharmaceutical clays. The high radioactive (Th, U), carcinogenic (Cr, Cu, Pb, Ni) and teratogenic (or birth defects) (Cu, Zn, Pb) elements contents in some Sabga geophagic clayey materials implied some pretreatment.

Highlights

The consumption of clayey materials occurs in almost all the continents in the world including North America [32], Central America [36], South America [1], Asia [2], Europe [35] and Africa [64, 23, 3, 44]
The main minerals identified by X-ray diffraction (XRD) in geophagic clayey materials (Figure 4) are a 14.12 Å phase considered as 2:1 phyllosilicate group mineral, a 7.18 Å phase assigned to kaolinite and characteristic peaks of feldspar and quartz
The scanning electron microscopy (SEM) micrographs show that geophagic clayey materials are characterized by the presence of pseudospherical smectite aggregates with different shapes and sizes (Figure 6a, b, d)

Summary

Introduction

The consumption of clayey materials occurs in almost all the continents in the world including North America [32], Central America [36], South America [1], Asia [2], Europe [35] and Africa [64, 23, 3, 44]. The practice of consuming geophagic clayey materials is very common in many African countries including Cameroon, where several localities abound in edible geophagic clayey materials. Among the different clay minerals, kaolinite in Koussérie, Mayouom, Dschang and Moko; smectite in Baba and Sabga; and halloysite in Balengou [63, 60, 24, 25, 17, 18, 3, 22, 44] have been reported in Cameroon. As far as pharmaceutical applications of Sabga are concerned, we should keep in mind that fine smectite from Sabga is ingested by neighbouring populations (mainly by pregnant women). Geophagia has been of interest to researchers and analysts due to continued habitual, religious and cultural practices by diverse global communities in spite of reports contraindicating its purported benefits.

Methods

Results

Conclusion