Abstract <p>The structural features of Cu-poor bornite at the nanoscale and atomic resolution level are presented for the first time. It is shown by the example of the Volkovskoye type of copper-sulphide mineralization that the pink variety of the non-stoichiometric bornite has polyphase composition, contains tight intergrowths of relic high-temperature phases, cubic bornite and chalcocite-Q, representing products of solid solution decomposition at the nanoscale. Native copper nanoinclusions have been discovered within bornite for the first time. The results demonstrate that the first step of copper-sulfide mineralization formation was not lower than at <i>T</i> = 400–800°C. Also they indicate high informativeness of the studies at the nanoscale and importance of further investigations of non-stoichiometric bornites for solving the fundamental issues of solid solution structural-phase composition, genetic reconstructions for Volkovskoye type ores at the modern level and increasing the efficiency of copper-sulfide deposit mining.</p>