MODIFIED LATTICE-PARAMETER CURIE-TEMPERATURE DIAGRAMS FOR TITANOMAGNETITE TITANOMAGHEMITE WITHIN THE QUADRILATERAL FE3O4-FE2TIO4-FE2O3-FE2TIO5/

Magnetic and mineralogical data were obtained on a sequence of titanom agnetite - 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 Mossbauer, XRD (including Rietveld structure refinement), TEM/AEM, and magnetic data. The data indicate a sequence ranging from nearly unoxidized titanomagnetite to near end-member tit anomaghemite. Compositions of samples with intermediate values of oxid ation parameter, Z, varied significantly from those estimated using pr eviously determined relations between lattice parameters and compositi ons. The data of this study, in conjunction with those of selected ref erences, lead to more accurate contoured diagrams for Curie temperatur e and lattice parameter (as consistent with Vegard's law) for the quad rilateral Fe3O4-Fe2TiO4-Fe2O3-Fe2TiO5.