Hexaferrum, defined as an hcp Fe mineral containing varying amounts of Ru, Os, or Ir (Mochalov et al. 1998) was re-examined in the light of new analyses of similar alloys from the Loma Peguera and Loma Larga chromitites, in the central part of Loma Caribe peridotite, Cordillera Central of the Dominican Republic, together with a review of the phase chemistry in the Fe–Ni–Ir and Fe–Ru–Ir systems. We conclude that the hcp (Fe,Ir) mineral corresponds to the ε-phase of Raub et al. (1964) and should be differentiated from hexaferrum [(Fe,Os) and (Fe,Ru)] because it is separated by one to two miscibility gaps and therefore is not a continuous solid solution with Fe.
