An exfoliated fragment of a rock painting from Lesotho was analyzed by differentiated backscatter spectrometry to obtain the paint thickness, which ranged from about 2 to 6.5 m, and its empirical formula for stopping power calculations. Elemental composition was determined by PIXE. Fe-rich paint spots were red in color and Ca-rich ones, pinkish. Because of the chemical mobility of calcium, this paint component should become the focus to which conservation techniques should be directed.