Perovskite
| Perovskite | |
|---|---|
 |
|
| General | |
| Category | Oxide minerals |
|
Formula (repeating unit) |
CaTiO3 |
| Strunz classification | 4.CC.30 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pnma |
| Identification | |
| Formula mass | 135.96 g/mol |
| Color | Black, reddish brown, pale yellow, yellowish orange |
| Crystal habit | Pseudo cubic – crystals show a cubic outline |
| Twinning | complex penetration twins |
| Cleavage | [100] good, [010] good, [001] good |
| Fracture | Conchoidal |
| Mohs scale hardness | 5–5.5 |
| Luster | Adamantine to metallic; may be dull |
| Streak | grayish white |
| Diaphaneity | Transparent to opaque |
| Specific gravity | 3.98–4.26 |
| Optical properties | Biaxial (+) |
| Refractive index | nα=2.3, nβ=2.34, nγ=2.38 |
| Other characteristics | non-radioactive, non-magnetic |
| References | |
Perovskite (pronunciation: /pəˈrɒvskaɪt/) is a calcium titanium oxide mineral composed of calcium titanate (CaTiO3). The mineral was discovered in the Ural Mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist Lev Perovski (1792–1856).
It lends its name to the class of compounds which have the same type of crystal structure as CaTiO3 (XIIA2+VIB4+X2−3) known as the perovskite structure. The perovskite crystal structure was first described by Victor Goldschmidt in 1926, in his work on tolerance factors. The crystal structure was later published in 1945 from X-ray diffraction data on barium titanate by Helen Dick Megaw.
Found in the Earth’s mantle, perovskite’s occurrence at Khibina Massif is restricted to the under-saturated ultramafic rocks and foidolites, due to the instability in a paragenesis with feldspar. Perovskite occurs as small anhedral to subhedral crystals filling interstices between the rock-forming silicates.
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