Such was the case with the two specimens which Cyrus Harding had brought back, one of magnetic iron, not carbonated, the other a pyrite, also called sulphuret of iron.
Cyrus Smith mintaként hozott két ércdarabja közül is az egyik magnetit volt, vagyis oxigéntartalmú mágnesvaskő, a másik pedig pirit, azaz vas-diszulfid.