Ilmenite

Ilmenite is a common iron titanium oxide mineral with the chemical formula FeTiO3. It is one of the principal ore minerals of titanium and is widely distributed in igneous and metamorphic rocks as well as in placer deposits formed by the concentration of heavy minerals along coastlines. The mineral often occurs in association with magnetite, hematite, rutile, zircon, and monazite.

Chemically, ilmenite belongs to the ilmenite-hematite solid solution series. Its crystal structure is characteristic of the trigonal system, with iron(II) and titanium(IV) occupying alternating octahedral sites within a hexagonally closest-packed arrangement of oxygen. Commonly, ilmenite appears black to steel-gray, has a metallic to sub-metallic luster, and shows a hardness of about 5 to 6 on the Mohs scale. Its specific gravity is relatively high, typically around 4.7 to 4.9. It is weakly magnetic.

Geologically, ilmenite forms in a range of settings from mafic to felsic igneous rocks and can crystallize early in magmatic processes. It is a major source of titanium globally and is heavily exploited from heavy mineral sands deposits, particularly in coastal regions. Industrially, ilmenite concentrates are processed to produce titanium dioxide for pigments and, by further reduction, can be used to obtain metallic titanium.

The mineral is named after Ilmen Lake in the Ural region, from which it was first described.