Perovskite
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Perovskite (calcium titanium oxide, CaTiO3) is a relatively rare mineral occurring in orthorhombic (pseudocubic) crystals. Perovskite is found in contact metamorphic rocks and associated mafic intrusives, nepheline syenites, and rare carbonatites. Perovskite was discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named for Russian mineralogist, L. A. Perovski (1792-1856).
Under the high pressure conditions of the mantle the pyroxene enstatite, MgSiO3, is a perovskite polymorph and may be the most common mineral in the Earth.
It is also the name of a more general group of crystals which take the same structure. See perovskite structure for details. The basic chemical formula follows the pattern ABO3, where A and B are cations of different sizes (for example, LaMnO3). The idealized structure is approximately a face-centered cube, but differences in sizes between the A and B cations can distort the structure to an octahedral form.
The perovskite structure shares the property of ferroelectricity with garnet and olivine. Many superconducting ceramic materials share the structure.
References
- Mineral galleries (http://galleries.com/minerals/oxides/perovski/perovski.htm)
- Webmineral (http://webmineral.com/data/Perovskite.shtml)
- Science World (http://scienceworld.wolfram.com/chemistry/PerovskiteStructure.html)
- Univ. Wisc. (http://www.uwgb.edu/dutchs/PETROLGY/Perovskite%20Structure.HTM)