WDXRF Analysis of White Colour Pigments Used by Ancient Artists in Central Tanzania Rock Paintings

In central Tanzania, there are large numbers of ancient rock paintings which have been drawn mostly on shelter rocks. Different colours were used in the paintings including white paint. The pigments and the material used by ancient artists in making these colours were not known. This study aimed to determine the composition of the white colour and suggests the pigments and materials used in making the white colour. A technique namely WDXRF was used to determine the composition of white paint in order to suggest the pigment used while a CHN elemental analyser was used to determine the presence and amount of organic carbon in the samples. The results from the analysis of the rock sample were compared to the results of the analysis of the paint sample. White colour was found to be from chalk (CaCO3) and gypsum (CaSO4X2H2O). Both pigments were found to contain some amount of organic carbon in different concentration. Organic carbon in the pigment is related to the use of organic binders during the preparation of the colour.