Abstract: The mineral priderite has been examined by electron microprobe analysis and electron diffraction. The composition was approximately (K_0.97Ba_0.33)(Fe_1.17Ti_6.60Mg_0.23)O₁₆, which is in line with the observed superlattice periodicity of m = 5.88, there being inter-growths of m = 5 and m = 6 superstructures. A surprisingly high degree of lateral correlation between tunnel cations was noted.