Modified lattice parameter/Curie temperature diagrams for Titanomagnetite/titanomaghemite within the quadrilateral Fe 3 O 4 ‐ Fe 2 TiO 4 ‐Fe 2 O 3 ‐Fe 2 TiO 5

Magnetic and mineralogical data were obtained on a sequence of titanomagnetite‐titanomaghemite solid solutions from four basalt samples (0 to 70 Ma) dredged from four sites along a traverse normal to the mid‐Atlantic Ridge. Data which characterized magnetic iron oxides with the spinel structure include Mössbauer, XRD (including Rietveld structure refinement), TEM/AEM, and magnetic data. The data indicate a sequence ranging from nearly unoxidized titanomagnetite to near end‐member titanomaghemite. Compositions of samples with intermediate values of oxidation parameter, Z, varied significantly from those estimated using previously determined relations between lattice parameters and compositions. The data of this study, in conjunction with those of selected references, lead to more accurate contoured diagrams for Curie temperature and lattice parameter (as consistent with Vegard's law) for the quadrilateral Fe 3 O 4 ‐Fe 2 TiO 4 ‐Fe 2 O 3 ‐Fe 2 TiO 5 .