The article reports on the presence of minerals of the crichtonite group (MCG) in ooids of mineralized volcaniclastic rocks of the Rudnogorskoe iron deposit (Eastern Siberia). The ooids are characterized by a concentric-zoned structure of detrital component, expressed in a sequential change of hematite-smectite core → smectite-chlorite → chlorite-garnet → apatite-chlorite zones, which are rimmed by thin-layered magnetite. Rare crystalline MCG aggregates in ooids are found in the peripheral apatite-chlorite zone. Based on the chemical composition and Raman spectra, the MCG are identified as crichtonite and davidite-Ce. The following components are determined in the composition of crichtonite, wt.%: TiO2 63.73-70.69, FeO 18.03-23.58, SrO 2.24-4.03, CaO 2.22-4.10, MgO 0.33-1.02, Al2O3 up to 2.01, MnO up to 0.54 and Ce2O3 up to 1.88. Davidite-Ce typically occurs along the edges of crichtonite and contains, wt.%: TiO2 60.54-62.28, FeO 22.67-25.77, Ce2O3 3.18-5.0, La2O3 2.47-2.74 and SrO 0.58-0.64. The MCG also contain up to 4.69 wt.% UO2. Complex processes of breakdown of MCG and their replacement by anatase are accompanied by the formation of REE (anzaite-Ce) and U (uraninite) minerals and subsequent transformation of anatase to rutile. A sequence of mineral formation of the ooids indicates that the formation and growth of the MCG crystals is a result of lithification of accumulated Ti and trace elements during smectitization of basaltic clasts. Further processes of mineral transformation are associated with the transformation of crichtonite to simple Ti oxides and the precipitation of REE and U minerals. Titanite is a product of the final skarn stages of ore formation.