Raman and SEM Studies of Man-made Barium Copper Silicate Pigments in Ancient Chinese Artifacts

AbstractAncient Chinese objects from the eighth to the third centuries BC were studied by Raman microscopy and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX). They included blue glassy faience beads, blue or purple beads of vitreous sinter material high in lead and barium, earrings and octagonal sticks. Man-made Han blue (BaCuSi4O10) and Han purple (BaCuSi2O6 ) were identified by Raman microscopy, as was ultramarine blue in two faience beads. SEM-EDX studies on the compact bodies of one bead and one octagonal stick revealed vitreous and crystalline phases, the latter with the approximate composition (BaO)n·(CuO)m·2SiO2, n, m = 1 or 2. All objects were found to contain varying amounts of lead.