The Minas-Rio mining project, a joint venture of British conglomerate Anglo American, includes, in addition to an iron ore pipeline and a port, an iron ore mine in Conceição do Mato Dentro / MG. This article focus on documents authored by the Public Prosecutor’s Office, which were produced during the installation process of the enterprise. The aim is to investigate the field of relations and the set of practices envisaged by the analysis of the materiality produced by a Public Civil Inquiry (ICP). As a state technology, the documents are analyzed for their dynamics, effects and powers mobilized through the procedures – Audiences and Public Meetings – that aimed at the social participation and interlocution among agents inside and outside the State; and institutional artifacts – Legal Recommendations and Terms of Conduct Adjustments – that sought the negotiated resolution of the established conflicts.