Ilmenite
Ilmenite is the primary ore of titanium, a metal needed to make a variety of high-performance alloys. Most of the ilmenite mined worldwide is used to manufacture titanium dioxide, IiO2, an important pigment, whiting, and polishing abrasive.
Ilmenite has a high resistance to weathering. When rocks containing ilmenite weather, grains of ilmenite disperse with the sediment. The high specific gravity of these grains causes them to segregate during stream transport and accumulate as “heavy mineral sands”. These sands are black in color and easily recognized by geologists. “Black sand prospecting” has long been a method of finding heavy mineral placer deposits. Most commercially produced ilmenite is recovered by excavating or dredging these sands, which are then processed to remove the heavy mineral grains such as ilmenite, leucoxene, rutile, and zircon.
Chemical Composition of Ilmenite
Ilmenite’s ideal chemical composition is FeTiO3.
Physical Properties of Ilmenite
Ilmenite is a black mineral with a submetallic to metallic luster. With just a glance it can easily be confused with hematite and magnetite. The differentiation is easy. Hematite has a red streak, while ilmenite has a black streak. Magnetite is strongly magnetic, while ilmenite is not magnetic. Occasionally ilmenite is weakly magnetic, possibly from small amounts of included magnetite.
Ilmenite is usually more durable than the other minerals in the igneous rocks in which it is abundant. For that reason, the weathering debris produced during the weathering of these rocks is especially rich in ilmenite. Its relatively high specific gravity causes it to become concentrated in placer deposits like gold, gems, and other heavy minerals.
Chemical Classification
Color
Streak
Luster
Diaphaneity
Cleavage
Mohs Hardness
Specific Gravity
Diagnostic Properties
Chemical Composition
Crystal System
Uses
Oxide
Black
Black
Metallic, submetallic
Opaque
None
5.5 to 6
4.7 to 4.8
Streak; sometimes weakly magnetic
Iron titanium oxide - FeTiO3. Sometimes has significant amounts of magnesium and manganese in solid solution with the iron to yield a composition of (Fe,Mg,Mn)TiO3
Hexagonal
The primary ore of titanium. A minor source of iron. Used to make titanium dioxide.
Uses of Ilmenite
Ilmenite is the primary ore of titanium metal. Small amounts of titanium combined with certain metals will produce durable, high-strength, lightweight alloys. These alloys are used to manufacture a wide variety high-performance parts and tools. Examples include: aircraft parts, artificial joints for humans, and sporting equipment such as bicycle frames. About 5% of the ilmenite mined is used to produce titanium metal. Some ilmenite is also used to produce synthetic rutile, a form of titanium dioxide used to produce white, highly reflective pigments.
Most of the remaining ilmenite is used to make titanium dioxide, an inert, white, highly reflective material. The most important use of titanium dioxide is as a whiting. Whitings are white, highly reflective materials that are ground to a powder and used as pigments.