Its most common mineral, perovskite, lends its name to this important group of oxides. The importance of this group is two fold. First, every member of this group has rare earth metals as trace elements in their structures and second, the structure of this group is unique and many ceramic, synthetic and useful substances can be created using the structure. The Perovskite Group is a group of oxides with a general formula of AXO3. The A can be either cerium, calcium, sodium, strontium, lead and/or various rare earth metals. The X site can be occupied by titanium, niobium and/or iron. All members of this group have the same basic structure.
This simplified ideal structure is isometric in symmetry. Members of this group would all be isometric if it were not for the fact that the octahedrons of most of the natural members of the group are twisted or rotated so as to kink or bend the structure. The twisting or bending is to accommodate the large ions between the octahedrons. The result is a variety of symmetries from isometric to tetragonal to orthorhombic to monoclinic depending on the degree of distortion to the basic ideal structure. Most perovskite minerals show some pseudocubic tendencies due to the close to, but not quite, isometric structure.
|Oka, Quebec, Canada
|Khibina, Kola Peninsula, Russia
|Lueshe, Democratic Republic of the Congo (former Zaire)
|Crni Kaman, Macedonia
|Slatoust district, Ural Mountains, Russia
|Murun complex, Russia
There are several synthetic crystals that have been made with the perovskite structure. These synthetics have a wide range of electrical ceramic uses from insulators right on through to superconducting material. Due to these uses and the increasing need for rare earth metals, the Perovskite Group will continue to be important and intensely studied.