ilmenite (ĭlˈmĕnĪt) [key], black mineral, iron titanium oxide, FeTiO3, crystallizing in the hexagonal system. It is sometimes found as tabular hexagonal crystals but occurs more commonly as small grains in igneous and metamorphic rocks and in sands derived from them. Ilmenite has been noted as an important constituent of lunar rocks. It is the commonest titanium mineral and is the most important source of this element and its compounds. Over 3 million tons of ilmenite are mined annually; important producers are the United States, Canada, Australia, and Norway.