Ferriallanite-(Ce), previously reported as “cerine” or iron-rich “allanite”, is the most common lanthanide mineral next to cerite-(Ce) at the Bastnäs Fe–Cu–REE deposit, Skinnskatteberg, Västmanland, Sweden. It is closely associated with cerite-(Ce), bastnäsite-(Ce), bastnäsite-(La), törnebohmite-(Ce), quartz, fluocerite-(Ce) and sulfide minerals. The Fe2O3 andFeO contents of ferriallanite-(Ce) are in the ranges 12.4–15.4 and 7.5–11.8 wt.%, respectively, and the dominant chemical variations are related to Fe2+↔ Mg and Ce↔ La substitutions. The concentrations of Th and U are extremely low,< 3 ppm. A complete, averaged structural chemical formula for one sample, with unit-cell parameters a 8.941 (4), b 5.799 (2), c 10.151 (6) Å, β 114.7 (6), V