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.

Mineral Data Base Index

GEOL 1010 Syllabus

GEOL 3010 Syllabus

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