In the context of archaeology, most of the time, micro-excavation for the study of furniture (metal, ceramics...) or archaeological context (incineration, bulk sampling) is performed without complete knowledge of the internal content, with the risk of damaging nested artefacts during the process. The use of medical imaging coupled with digital 3D technologies, has led to significant breakthroughs by allowing to refine the reading of complex artifacts. However, archaeologists may have difficulties in constructing a mental image in 3 dimensions from the axial and longitudinal sections obtained during medical imaging, and in the same way to visualize and manipulate a complex 3D object on screen, and an inability to simultaneously manipulate and analyze a 3D image, and a real object. Thereby, if digital technologies allow a 3D visualization (stereoscopic screen, VR headset ...), they are not without limiting the natural, intuitive and direct 3D perception of the archaeologist on the material or context being studied. We therefore propose a visualization system based on optical see-through augmented reality that associates real visualization of archaeological material with data from medical imaging. This represents a relevant approach for composite or corroded objects or contexts associating several objects such as cremations. The results presented in the paper identify adequate visualization modalities to allow archaeologist to estimate, with an acceptable error, the position of an internal element in a particular archaeological material, an Iron-Age cremation block inside a urn.