University of Colorado

Mineral Structure and Property Data

Perovskite Group


The Perovskite group is composed of the minerals perovskite CaTiO3), and MgSiO3 in the perovskite structure. The latter phase does not have a proper mineral name because we do not have natural sample of it, but it is generally believed to be the most abundant solid phase in the Earth, making up 70 to 80% of the lower mantle (670-2900 km depth).

The crystal structure of MgSiO3 perovskite. The structure is composed of an octahedrally coordinated Si or Ti atom and the Mg or Ca in irregular 10-coodination. The structure would ideally be cubic if the divalent cation were large enough, but both of the mineral forms are orthorhombic.


Perovskite Group Unit Cells


                Perovskite  MgSiO3
                CaTiO3       MgSiO3  

Form.Wt. 135.98 100.40 Z 4 4 CrystalSystem Orth Orth PointGroup mmm mmm SpaceGroup Pbnm Pbnm UnitCell a(Å) 5.3670 4.7754 b(Å) 5.4439 4.9292 c(Å) 7.6438 6.8969 Vol(Å3) 223.33 162.35 MolarVol 33.63 24.445 Density 4.044 4.107 Thermal Expansion(Volumetric) alpha 22.0 a0 0.2200

Perovskite Group Cation Sites


End-Member          Perovskite             MgSiO3 


C.N. 10 6 8 6 Occupant Ca Ti Mg Si Point Sym. m -1 m -1 Wyckoff Not. 4c 4b 4c 4b Frac.Coord. x .000 0 .974 0 y .030 1/2 .063 1/2 z 1/4 0 1/4 0 Distances Cation-Ox O1 (1)2.794 (2)1.924 (1)2.124 (2)1.789 O1 (1)2.664 (1)2.099 O1 (1)2.883 O1 (1)2.486 O2 (2)2.584 (2)1.924 (2)2.196 (2)1.823 O2 (2)2.553 (2)1.928 (2)2.062 (2)1.757 O2 (2)2.685 (2)2.471 Mean 2.647 1.926 2.210 1.790 sigma .121 .002 .169 .029 Poly.Vol. 37.112 9.492 20.264 7.635 Q.E. 1.0019 1.0011 Ang.Var. 6.7 2.3 Site Energy -950. -4256. -1132. -4527.


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