Abstract: Titanomaghemite occurs in a relatively fresh doleritic intrusion in an area of Precambrian gneiss in Minas Gerais, Brazil. It hosts exsolution lamellae of ilmenite and contains more than 90% of the iron in the ferric form. It is more resistant to weathering than the ilmenite and is inherited virtually unaltered by the resulting soils. Titanomaghemite, extracted as grains from a weathered rind of the rock, has lattice parameter a₀ = 0.8348(3) nm and has a canted spin structure due to substitution of non-magnetic ions on tetrahedral and octahedral sites of the spinel structure. The average canting angle is 32 ± 3° and canting occurs predominantly on the octahedral iron sublattice. Its formula, based on microprobe analysis and Mössbauer spectroscopy may be expressed as: [Fe_0.77Ti_0.22Zn_0.01]{Fe_1.19Ti_0.26Mn_0.02Al_0.04□_0.49}O₄ where [] and {} denote ions on tetrahedral and octahedral sites, respectively. The spontaneous magnetization of the mineral is 36(3) J/T/kg.