Structural parameters of iron iodine boracite, Fe3B7O13I, [cubic with space group F[image omitted]3c at 373 K, lattice parameters acub = 12.22869(18) Å; rhombohedral with space group R3c at 10 K, lattice parameters ahex = 8.64534(21) and chex = 21.2035(8) Å] was refined from X-ray powder diffraction data; Rprofile = 2.4% (373 K) and 3.0% (10 K). For precise lattice parameter determination, the structure at low temperature was refined by using a sample with silicon as reference. The refinements show that the (averaged) difference between the two iron iodine distances increases from cubic → orthorhombic → rhombohedral structure from 0 Å → 0.20(1) ↠ 0.32(4) Å, respectively.