A new deposit of massive, specular micaceous haematite, found associated with Neoproterozoic diapiric thrust faults and with hydrothermally recrystallised calcarenite members of the Etina Formation, was mapped at the Rainy Day prospect, which is located 5.5 km along strike to the north of the Warrakimbo copper mine, where substantial similar mineralisation occurs. Low temperature, moderate pressure epigenetic replacement of siderite or ferroan calcite, probably during the structurally induced creation of porosity within the carbonate host rocks, is favoured as a likely genetic mechanism. It is considered that the widely distributed late/post Delamerian hydrothermal epigenetic willemite mineralisation and associated pervasive haematitic alteration in younger Cambrian carbonates has a similar mode of occurrence and emplacement temperature.