In 2009, part of a ‘slave shackle’ was recovered from archaeological investigations at Trianon, an indentured labourer site on Mauritius dated from the beginning of the nineteenth century. This paper presents the results of a metallurgical assessment of the artefact, thought to represent colonial ironwork, a category that has hitherto remained understudied. The results are incorporated into the wider archaeological and historical evidence from Trianon, highlighting the value of studying colonial ironwork in context.