MATERIALS AND SYNTHESIS OF ANCIENT CHINA- THE PRODUCTION OF BARIUM COPPER SILICATES USED AS BLUE AND PURPLE PIGMENTS

摘要

From the late Spring and Autumn Period (770-475 B.C.) to the Han Dynasty period (206 B.C.-220 A.D.) blue and purple barium-copper-silicate pigments were produced in ancient China. They were used for paintings, production of faience and for the manufacturing compact body artifacts. In modern times the investigation of the BaO-CuO-SiO_2 phase diagram established the existence 4 ternary phases identical with ancient pigment phases: BaCu_2Si_2O_7 (Chinese Dark Blue), BaCuSi_4O_(10) (Chinese (Han) Blue), BaCuSi_2O_6 (Chinese (Han) Purple) and Ba_2CuSi_2O_7 (light blue, not named as yet), which except for Ba_2CuSi_2O_7 were in ancient times often prepared phase pure or nearly phase pure from mineral starting materials via stoichiometry controlled syntheses at temperatures of 900 - 1000 ℃. High quality products were achieved via cycles of grinding and heating using a lead oxide flux. Chinese (Han) Blue Chinese (Han) Purple Chinese Dark Blue The lecture will also report on archaeometrical studies of original objects. Recently we applied portable sampling by laser ablation (LA) and ICPMS to original objects for an isotope and trace element provenancing, by which a gross mapping of the mines for the starting materials and of the workshops locations in ancient China could be achieved. Support from the Sino Swiss Science and Technology Cooperation Program (IP 10-092010) is gratefully acknowledged.