Mineral sands are within a class of ore deposits that contain heavy minerals such as ilmenite, zircon, leucoxene, and rutile. The most important, naturally occurring minerals that are mined to produce titanium dioxide (TiO2) feedstock are ilmenite, leucoxene and rutile. The minerals are either used as feedstock in their natural form or in an upgraded form, such as synthetic rutile and titania slag, which are produced through the secondary processing of ilmenite.