Fibre products, such as textiles and animal pelts, are often recovered in the corrosion crust of archaeological metal artefacts. Because clothed burials are an important resource for the study of past societies, accurate fibre identification is important. However, extreme mineralisation of animal fibres can render microscopic visualisation difficult for species identification. Peptide mass fingerprinting (PMF) has been successfully used to identify the species origin in both collagen and keratin-made archaeological artefacts. The approach requires little material but the state of degradation (protein hydrolysis) is a limiting factor as it might impact on the identification of key markers. In this study we analysed pelt and textile fragments found in association with copper-alloy objects with different degrees of mineralisation; samples were obtained from a Viking-Age (10th c.) grave in Britain and from a burial in Mongolia (3rd c. BC to 2nd c. AD). Species identification was possible in all but one sample, revealing PMF can be applied to corrosion products, thereby further expanding the value of these objects for textile research.