天梯山石窟9窟彩塑与壁画地仗矿物及颜料分析

Analysis of pigments and clay of the polychrome statue and wall paintings in the No.9 Tiantishan Grotto

天梯山石窟,即北凉石窟,在国内史学界誉为中国古代石窟鼻祖。据考证,9窟彩塑与壁画制作始于唐代,后经历代多次重绘。针对目前彩塑与壁画的保存现状及需要修复的状况,本研究运用现代分析仪器与技术,对9窟现存的彩塑、壁画进行了科学分析。其中,对彩塑及壁画地仗土层矿物进行了X射线衍射分析,对重层彩绘颜料进行了X射线衍射、X射线荧光分析;另外,对清理彩塑地仗时发现的植物茎秆及附属物,采用偏光显微分析技术进行了材质鉴定。分析和鉴定结果表明:9窟现存彩塑及壁画地仗土层具有相同的矿物组成,基本包括石英、长石(斜长石、少量的K-长石)、云母(白云母、绿泥石、伊利石、斜绿泥石)、方解石、少量石膏,并确定植物茎秆材质为稻草;在使用的彩绘中,黑色为墨,红色颜料有朱砂、铅丹和铁红,蓝色颜料为石青,白色颜料以方解石为主,有少量的石膏。本结果可为后期天梯山石窟的全面复原修复提供参考资料。

Tiantishan Grottoes, also called the Northern Liang Grottoes, are the oldest Grottoes in China. According to records,the no. 9 grotto was created during the Tang Dynasty and its polychrome statue and wall paintings were repainted several times in the following dynasties. To aid preservation and conservation of the polychrome statue and wall paintings, modern scientific techniques were used to analyze the polychrome statue and the wall clay. X - ray diffraction and X- ray fluorescence were used to analyze the pigments, and polarized light microscopy was used to analyze the plant stems and other components mixed in the clay, in order to identify the materials. The analytical re- suits indicate that the polychrome statue and the wall paintings have same clay compositions, consisting of quartz, feldspar （ plaqioclase and a small amount of k - feldspar）, mica （ muscovite, chlorite, illite, clinochlore） , calcite and a small amount of gypsum. The plant stems found in the clay are straw. The pigments used are Chinese ink as black ; cinnabar, red Lead and iron oxide as red, azurite as blue and calcite with a small amount of gypsum as white. These results provide a basis for future restoration of the Tiantishan Grottoes.