A multi-technique characterization and provenance study of the pigments used in San rock art, South Africa

During the course of a conservation project at the rock shelter known as RSA TYN2 (Eastern Cape, South Africa), a sample of 33 painted fragments that had become detached from the wall were collected. They have been studied using a multi-technique approach (optical microscopy, SEM-EDS, Raman spectroscopy and FTIR), with the aim of achieving a better understanding of their paint stratigraphy, composition, and provenance. The paintings are on a Clarens Formation sandstone and are embedded in calcium sulphates and oxalates. The red pigments show two different ‘hues’, corresponding to two different compositions. The light red is a red ochre, possibly pure, which is probably a degradation product of the Clarens Formation sandstone. The dark red contains more iron oxides and may be a mixture between the red ochre and pure haematite. Because of the presence of crystals which may be identified as augite we suggest this haematite came from the basaltic upper part of the Drakensberg, at least 4 km away from the rock shelter. The black pigments have been identified as carbon black, that is to say, incomplete combustion products of organic compounds, and are radiocarbon dated to between 2120 and 1890 cal BP, making these samples the oldest directly dated South African rock art.     

Sensitivity of bulk sedimentary stable carbon isotopes to prehistoric forest clearance and maize agriculture

The stable carbon isotope compositions (δ¹³C) of tropical lake sediments and soils have been used to reconstruct the occurrence of prehistoric maize cultivation and its relative importance through time. This study assesses some of the possible variables affecting the response of lake sediment bulk organic carbon isotope (δ¹³C_TOC) values to variations in the scale of prehistoric maize cultivation and the potential of this proxy to yield quantitative estimates of the scale of prehistoric maize agriculture in small tropical watersheds. High resolution analyses of δ¹³C_TOC values, maize pollen concentrations, and mineral influx were conducted on sediments deposited during a ∼220 year period of prehistoric maize agriculture in the watershed of Laguna Castilla, a small lake in the mid-elevations of the Cordillera Central, Dominican Republic. Close correspondence between δ¹³C_TOC values and maize pollen concentrations in the Laguna Castilla sediment record indicates a close relationship between the isotopic values and the scale of prehistoric maize cultivation. Correlations between the δ¹³C_TOC signature and mineral influx indicate that the isotope record is also sensitive to variations in allochthonous carbon delivery. This study establishes that sedimentary δ¹³C_TOC values can provide a highly sensitive proxy of the spatial scale of prehistoric maize agriculture in small tropical watersheds, but emphasizes the need for a better understanding of sediment dynamics and carbon cycling in anthropogenically modified landscapes before this proxy can be widely employed in diverse archaeological settings.     

埃及晚期的木基质彩画：赛加拉和法国博物馆

埃及文明在矿物方面的知识总是超出了我们的想象。这方面就包括使用多种黄色矿物绘制颜色相近的色彩。对这些颜料的准确鉴定将拓展人们在彩画方面的研究。画家所使用的颜料非常丰富,除了同时代直接从埃及地面采集的自然颜料外,还有大量像埃及蓝这类合成颜料的应用。对法国的这些藏品的研究将使人们可以追溯几个世纪以来这些颜料的演变和替代过程以及一些从其它地区尤其是东方国家引进颜料的过程。一些颜料的稳定性及其它特性使得其保存状况令人惊讶。卢浮宫博物馆在塞加拉的任务是进行一个埃及晚期（公元前378年一公元前341年）典型群葬墓的发掘工作。发掘出的木质棺材上记载了该墓葬的埋藏时间是Nectanebo二世法老执政的第2年,这是埃及第三十王朝的最后一任法老。该研究涉及以木质为基材的出土物,它包括二十个完整的或破碎成碎块的像盒子一样的棺材。研究通过在双筒显微镜下对文物进行微量取样,而后将样品进行扫描电子显微镜一能谱分析以及显微拉曼光谱分析,从而确定样品中矿物的成分。此外还对样品进行微量化学分析以确定其残存的痕量胶料。彩色颜料包括埃及彩画同时代的传统颜料一黑色,白色,红色,黄色,蓝色,绿色和镀金,同时还包括一些不常见的粉红色或橘色颜料,它是一种外来的、易碎的颜料,成分为五硫化二砷,又称雄黄。     

战国秦汉时期制铁耐火材料的矿物组织与含量分析

战国秦汉时期是中国古代生铁与生铁制钢技术体系的发端与形成期,制铁耐火材料为发达的生铁与生铁制钢技术体系提供了结构、化学、热性能上的技术保障,具有重要的作用。但目前制铁耐火材料的研究较少,影响了对中国古代钢铁技术的全面认识。本研究对战国秦汉时期出土的制铁耐火材料开展了文献、田野考察和矿相分析,科学认知其微观结构,认为战国秦汉时期制铁耐火材料以黏土质材料为主,使用了砂质材料,但尚未出现砂泥混合质材料。同时,炉壁、铸铁范、鼓风管之间的矿物显微组织和含量差异较大,表明战国秦汉时期工匠已能根据性能需求的不同制作不同的耐火材料用于不同的制铁生产环节。     

山西太原纯阳宫所藏明代一尊星宿彩塑颜料分析

利用现代科技分析手段提取古代彩塑信息并与文献结合,可以推断其工艺、材料和制作时间,进而确定其历史价值、科学价值和艺术价值,为艺术史研究和保护修复提供信息与帮助。因此,本工作利用三维视频显微镜(3D Video Microscope)、偏光显微镜(PLM)、拉曼光谱(Raman)、扫描电子显微镜与能谱仪(SEMEDX)、X-射线衍射仪(XRD)和大腔体微束X-射线荧光光谱仪(XRF)等分析了山西太原纯阳宫所藏一尊明代道教星宿彩塑脱落样品,发现彩塑经过多次重绘。其中星宿足部经过四次重绘,从胎体至表面层使用的黑色颜料为炭黑(C),绿色颜料为氯铜矿(CuCl_2·3Cu(OH)_2),白色颜料为铅白(PbCO_3),褐红色颜料为靛青(C_6H_(10)N_2O_2)与黄丹(PbO)的混合物。彩塑头部经过两次重绘,分别使用了群青(Na_(6-8)Al_6Si_6O_(24)(S_(2-4))和靛青。彩塑躯干部位表层红色颜料为朱砂(HgS)和铅丹(Pb_3O_4)的混合物,黄色颜料为铅铬黄(PbCrO_4),蓝色颜料为群青,绿色颜料为铅铬黄(PbCrO_4)与群青的混合物。彩塑白粉层成分为石英(SiO_2)与高岭土(Al_2Si_2O_7·2H_2O)的混合物。分析结果表明,此尊星宿彩塑在过去的数百年间曾经多次重绘或修葺,根据不同白粉层成分组成相近判断,保存该彩塑群的寺观有将高岭土作为白粉层的传统。研究结果可为保护材料和修复技术的选择提供信息和依据。     

清代外销油画《镇海楼》颜料的分析鉴别

为研究清代外销油画《镇海楼》颜料成分及颜料层状况,利用数码显微镜、傅立叶红外光谱、X射线荧光光谱并结合扫描电镜能谱技术对其进行观察和检测。研究表明,此幅清代油画中红色颜料分别为朱砂和赭石,蓝色颜料为普鲁士蓝,黄色颜料则为雄黄和铁黄,白色颜料为铅白。通过显微镜观察发现画中部分颜料层有开裂和局部剥落现象。本研究分析为中国清代油画的材料技法、保护修复及美术史研究提供了极具价值的信息。     

山东临淄山王村俑坑出土陶质彩绘颜料初步分析

2008年5月山东临淄山王村俑坑出土了数量较多的彩绘陶质文物,为了了解彩绘颜料结构和成分,采用粉末偏光显微法、剖面观察结合拉曼光谱分析对彩绘文物表面颜料样品进行分析。结果表明,这批陶质文物表面彩绘是以白灰做地仗层,由碳酸钙、白土、铁黑（Fe₃O₄）、铁红（Fe₂O₃）、朱砂等颜料调和而成,且厚度不均。在个别样品中发现了少量的中国蓝颗粒(BaCuSi₄O₁₀),这是这次分析中较为重要的发现,此分析结果也可为考古研究提供科学信息。