The mineral brookite is a titanium oxide with the chemical formula TiO2. The crystal system of brookite is orthorombic. It is an orange to brown mineral with a hardness of 5.5 to 6 and an average density of 4.11. It is not radioactive. Brookiet is named after Henry James Brooke (1771-1857), a British mineralogist. Brookiet is found in, among others, Hot Springs, Arkansas, USA. Other TiO2 minerals are rutile and anatase.