perovskite

Yellow, brown, or greyish-black orthorhombic mineral, CaTiO₃, which sometimes contains cerium. Other minerals that have a similar structure are said to have the perovskite structure. The term also refers to MgSiO₃ with the perovskite structure, the principal mineral that makes up the Earth's lower mantle.

CaTiO₃ perovskite occurs primarily as a minor constituent of some igneous rocks in the Earth's crust and mantle and in some meteorites. MgSiO₃ perovskite has the same chemical composition as pyroxene, a principal constituent of the upper mantle. But the extreme pressures in the lower mantle cause the oxygen atoms to be packed more tightly together than in pyroxene, giving rise to the perovskite form of MgSiO₃ in the lower mantle.

The perovskite structure of MgSiO₃ was discovered in diamond-anvil cell experiments in which upper mantle materials that are stable at the Earth's surface, such as the mineral pyroxene, are squeezed at high pressures to simulate the Earth's interior. Although this mineral does not occur naturally at the Earth's surface it is thought to be the most abundant mineral in the mantle, and therefore Earth's most abundant mineral.