Abstract: Magnetite grains with exsolved ilmenite lamellae may be replaced by pyrite or carbonate in phlogopitites of the Catalão I carbonatite complex, Goiás State, Brazil. The ilmenite is transformed in part to priderite and sometimes to rutile. Priderite occurs as small anhedral grains (< 0.2mm) or composite crystals associated with ilmenite and rutile. Chalcopyrite, magnetite, monazite, and pyrochlore also occur inside the area of original magnetite grains. The priderite belongs to the K₂FeTi₇O₁₆-BaFeTi₇O₁₆ series with K/(K + Ba) ranging from 1.0 to 0.53. The highest contents for other elements are: V₂O₃ 2.65, Cr₂O₃ 4.1, and Nb₂O₅ 1.98 wt.%. Priderites associated with magnetite have the highest V, Cr, and Nb contents whereas others have the highest Ba content. Zoning characterized by K-Ba substitution is patchy but always present. V-and Cr-poor priderites are similar in composition to priderites from lamproites, and the V- and Cr-rich ones are compositionally similar to hollandite-group minerals found in kimberlites.