The conceptual ability to source, combine, and store substances that enhance technology or social practices represents a benchmark in the evolution of complex human cognition. Excavations in 2008 at Blombos Cave, South Africa, revealed a processing workshop where a liquefied ochre-rich mixture was produced and stored in two Haliotis midae (abalone) shells 100,000 years ago. Ochre, bone, charcoal, grindstones, and hammerstones form a composite part of this production toolkit. The application of the mixture is unknown, but possibilities include decoration and skin protection.

The mission of cultural heritage institutions is to preserve and protect artifacts from the distant or more recent past for the enjoyment and education of current and future generations. In order to fulfill this mission in a professional manner, detailed knowledge on alteration phenomena of various kinds that gradually and unobtrusively are taking place at or below the surface of these objects is required. In order to be able to investigate the nature of these chemical transformations, that sometimes lead to the formation of microscopically thin alteration layers, the use of state-of-the-art microanalytical methods is required. Next to being able to provide information on the composition of various materials at or just below the surface, these methods also must be able to deliver highly specific information on the nature of the chemical compounds that are locally encountered. In this respect, our recent experience shows that the use of a combination of synchrotron X-ray based spectroscopic and imaging methods such as X-ray fluorescence analysis, X-ray absorption spectroscopy and X-ray diffraction can reveal significantly new information of certain alteration processes that have remained enigmatic for a long time. Concrete examples to be discussed is the darkening of originally yellow lead chromate paint layers, as encountered in paintings of V. Van Gogh [1,2] and the blackening of red cinnabar-based paint layers in works of Rubens [3]. In both cases, one or more microscopically thin alteration layers were encountered that are responsible for the colour and that contain resp. the metals Cr and Hg in other chemical environments that what they were originally. Born in the early Seventies for medical applications, X-ray Computed Tomography is currently playing an increasingly important role in the field of Cultural Heritage diagnostics. In fact it represents a powerful non-destructive investigation technique, capable of displaying in a three-dimensional way the volume and the internal structure of the investigated objects, also thanks to modern 3D rendering techniques. This kind of information is very important for determining adequate conservation and restoration procedures [1] [2]. The first attempts in adopting this technique for Cultural Heritage analysis have been done by means of medical CT scanners, usually with courtesy and permission of an hospital. However, medical scanners are optimized for the human body (composed mainly by water) and cannot be successfully used on dissimilar objects like those of interest in the Cultural Heritage field. Moreover, it is difficult to move valuable works of art outside the museum in which they are located. The great variety of size, shape and composition that is typical of archaeological findings and art objects requires the development of tomographic systems specifically designed for Cultural Heritage analysis and movable on-site, if necessary. In order to fulfill this request, our research group has setup several CT systems, that make us able to perform high resolution m...