Ilmenite
Ilmenite is an iron-titanium oxide that is abundant in some lunar basalts and present in many igneous meteorites.
Ilmenite is a black, weakly magnetic oxide of iron and titanium, FeTiO3. On Earth it is mined as a source of titanium.
On the Moon, ilmenite is unusually abundant. Some mare basalts collected by Apollo astronauts contain more than 10 per cent titanium oxide, much of it in ilmenite, and these high-titanium basalts are a distinctive lunar rock type. Ilmenite has been suggested as a resource for future lunar bases, because oxygen can be extracted from it by chemical reaction. It is also found in lunar meteorites, eucrites, shergottites and some angrites.
Ilmenite often forms flat plates or needles that crystallised late in a cooling lava. Under reflected light on a polished section, it looks grey-brown and shows distinctive anisotropy, changing shade as the microscope stage is turned. Its composition, together with that of neighbouring magnetite or spinel, helps estimate temperature and oxygen levels in a magma.
Related terms
Level: Enthusiast Teens and adults