Ilmenite

Ilmenite is an important ore of titanium, which is used to make things like tools, bicycle frames, artificial human joints, and high performance parts. Ilmenite is also used to make titanium dioxide, which is a white, reflective material. It is typically used as a pigment for anything from paper to toothpaste, after the mineral is ground into a powder and impurities are removed.

Ilmenite crystallizes in the trigonal system. The ilmenite crystal structure consists of an ordered derivative of the corundum structure; in corundum all cations are identical but in ilmenite Fe and Ti ions occupy alternating layers perpendicular to the trigonal c axis. Containing high spin ferrous centers, ilmenite is paramagnetic. Ilmenite is commonly recognized in altered igneous rocks by the presence of a white alteration product, the pseudo-mineral leucoxene. Often ilmenites are rimmed with leucoxene, which allows ilmenite to be distinguished from magnetite and other iron-titanium oxides. The example shown in the image at right is typical of leucoxene-rimmed ilmenite. In reflected light it may be distinguished from magnetite by more pronounced reflection pleochroism and a brown-pink tinge. Samples of ilmenite exhibit a weak response to a hand magnet.