Perovskite crystal structure. Perovskite is the name for the mineral calcium titanium oxide (CaTiO3). It forms a crystal structure that is very common in oxide minerals, which has become known as the perovskite structure. The unit cell (repeating crystal unit, outlined in red) has titanium ions (blue) at the corners of a cube, a calcium ion (grey) at the centre of the cube and oxygen ion (red) arranged in an octahedron around the calcium, on the faces of the cube.