Both anatase and brookite belong to the oxide minerals of titanium, which are two homogenous and polymorphic variants of rutile minerals. Anatase is a very rare mineral. Its composition often contains impurities such as ferric oxide and tantalum, niobium, étain, and manganese. Il appartient au système cristallin tétragonal. Transparent to opaque, hardness is 5.5-6.0. [...]
