A Hallstatt period burial mound (tumulus) in Schandorf, Burgenland, Austria, was opened and archaeologically investigated in 2021. Not only numerous pottery fragments, but also some garment buttons were found, one of which was provided for metallographic examinations, aiming at identifying the method of manufacture: soldering, riveting, casting? Prior to the metallographic examinations, micro-computed tomography (μm CT) was carried out at a resolution of 5 μm. The Figures show that large areas are oxidized. It was, however, found that metallic portions still existed. The overall appearance suggests investment casting as the manufacturing method. Analytical measurements revealed that the material is tin bronze. Despite severe corrosion, the metallographic sections still exhibit a clearly recognizable cast structure. There are presumably two types of corrosion: first, high temperature corrosion, which resulted in the formation of bronze oxides in the grain boundary areas during the cremation, and, second, corrosion in an aqueous environment, during which malachite formed.