TiO₂
Anatase is a polymorph that transforms into rutile when subjected to temperatures of around 915 degrees Celsius. It is brown to black or yellow to blue in hue. Anatase is the rarest type of titanium dioxide, yet its hardness, density, and lustre are almost identical to rutile. However, the cleavage and crystal habit of the two minerals separate them from one another. The structure of both Anatase and rutile is tetragonal, but Anatase has octahedrons that share four edges to produce the four-fold axis. Anatase streaks typically accompany quartz. Quartz and Anatase are popular among collectors of gems and minerals due to their dazzling lustres. Anatase is also used for the white colouring of paints, paper, and ceramics. Howeverceramics. However, due to its lower absorption rate than rutile, Anatase should not use outdoors.
