Characterization of the Geophagic Materials and Their Associated Rocks and Soils from Anfoega, Ghana

Abstract

This study was conducted to examine the physico-chemical and mineralogical properties of geophagic materials and their associated rocks and soils from Anfoega, Ghana. The geophagic materials were sampled from pits >10 m deep overlain by massive sandstones and shallow soils which were also sampled. The pH of the geophagic materials was strongly acid. The pH of the soils from the three sites was slightly to moderately acid, that of the fourth site was moderately acid in the surface but strongly acid in the lower layers. While the geophagic materials were enriched with clay, the soil samples contained high amounts of sand. The CEC of the geophagic materials (18.0 to 23.2 cmol_c kg^-1) was higher than that of the soils (5.3 to 22.6 cmol_c kg^-1). Thin sections of the rocks showed high amounts of quartz and accessory feldspars and sericite. The geophagic materials contained high amounts of clay (with >79% SiO₂), quartz, feldspars and sericite. X-ray diffractograms of the geophagic materials, rocks and soils were dominated by quartz, kaolinite, muscovite and feldspars. The sialic minerals in the geophagic materials (shales) were probably leached from the overlying sandstones. The mineralogy of the soils indicated that they were formed in-situ from the underlying sandstones.