Mummified animal skin with tar content from the castle of the late medieval town of Novo Brdo (Central Balkans)

Organic materials are rare in the archaeological settlement context of the central Balkan area. A unique assemblage consisting of mummified animal skin with preserved hair, filled with resinous material, and four smaller pieces of animal skin with preserved hair was discovered during archaeological excavations of the Novo Brdo castle in 2015. The late medieval town of Novo Brdo was an important mining centre of the Balkans (and the entire Europe) for the production and distribution of silver ore. The archaeological context for the mummified animal skin was the workshop for the production of lead projectiles, situated in the northeast corner of the castle's Great Hall, and it can be reliably dated to the first half of 1455. The finds were first subjected to macroscopic analysis, which included observations on the skinning method and the details of use. Applying light and SEM microscopy, a comparative set of hair surface structure images from seven mammal species was created, and a Fourier Transform Infrared Spectroscopy analysis of resinous material was performed. By comparing it with the reference images of hair microstructure, the animal skin was identified as goat, while the FTIR of the resinous material identified pine tar. The four smaller pieces of skin probably originated from one individual sheep. The tar stored in the goat skin was most likely used in the impregnation of wooden structures or even to illuminate buildings and ramparts of the Novo Brdo castle, although other purposes, such as being used as a lubricant for weapons, cannot be completely ruled out.