Illimnite is a mineral composed primarily of iron titanium oxide, with the chemical formula (Fe,Ti)O₃. It is often found in igneous rocks and is typically associated with other titanium-bearing minerals. Illimnite is of interest in various industrial applications, particularly in the production of titanium dioxide, which is used as a white pigment in paints, coatings, and plastics. Its name is derived from the locality of its discovery, near the town of Ilmen in Russia.