Chemical, mineralogical and physical study of Late Iron Age ceramics from Nditam: Cameroon (West central Africa)

Abstract

This paper studied Late Iron Age ceramic fragments from Nditam village (Centre Region, Cameroon), the technological features and deduced the type of the raw materials used to produce them by combining different analytical techniques based on X-ray fluorescence, powder X-ray diffraction, thermogravimetry, polarized optical microscopy, spectrophotometry and hydric tests. Macroscopic observations suggest the existence of three types of ceramics according to their colour, black, greyish and red, in the two opposite surfaces, outer (or external) and inner (internal). The chemistry indicates that non-calcareous clayey material was used for ceramic production. The correlation between mineralogy, petrography and the geology of the region suggests a local production of ceramics. Moreover, the chemistry of the samples confirms the existence of the three macroscopic groups and suggests the use of local raw materials for their production. From the mineralogical point of view, quartz, feldspar and mica (biotite and muscovite) were identified in all the samples, while kaolinite and amphibole were detected in some of them. The differences in the mineralogy may indicate some variations in the firing temperature, being lower in the ceramics containing kaolinite compared to the other samples. All the samples have similar water absorption behaviour. According to the colours of the ceramics, a prevalence of oxidising firing conditions was present in the kilns. However, partial reducing and short duration firing conditions were also possible. Comparative study with the mineralogy of ethnographic ceramics from southern Cameroon shows some similarities and suggests a continuity in the use of different local clay pits in this region over time.