University of Colorado

Mineral Structure and Property Data

Ilmenite Group


The Ilmenite group is composed of the minerals ilmenite and pyrophanite. The crystal structure is an ordered derivative of the corundum structure. In addition to ilmenite and pyrophanite, MgSiO3 also adopts this structure at pressures of the transition zone in the mantle.

The crystal structure of ilmenite.


Ilmenite Group Unit Cells

                Ilmenite    Pyrophanite
                FeTiO3      MnTiO3

Form.Wt. 151.75 150.84 Z 6 6 CrystalSystem Trig Trig PointGroup -3 -3 SpaceGroup R-3 R-3 UnitCell a(Å) 5.0884 5.137 c(Å) 14.0885 14.283 Vol 315.84 326.41 MolarVol 31.705 32.766 Density 4.786 4.603 Thermal Expansion(Volumetric) alpha 27.9 a0 0.2689 a1 0.3482 a2 0.0000 Elastic Properties Ks(GPa) G(Gpa)

Ilmenite Group Divalent Sites.


End-Member          Ilmenite          Pyrophanite          MgSiO3 

C.N.                6                 6                    6
Occupant            Fe                Mn                   Mg

Point Sym.          3                 3                    3
Wyckoff Not.        6c                6c                   6c

Frac.Coord.
x                   0                 0                    0
y                   0                 0                    0
z                   .35537            .3570                .3597

Distances
1(3)                2.201             2.230                2.163
2(3)                2.078             2.024                1.990

Mean                2.081             2.127                2.076
sigma                .068              .113                 .095

Poly.Vol.          12.562            12.336               11.238
Q.E.               1.0271            1.0289               1.0429
Ang. Var.          91.8              91.8                 143.4

Site Energy       -1179.            -1220.               -1183.

Ilmenite Group Tetravalent Sites.


End-Member          Ilmenite          Pyrophanite          MgSiO3 

C.N.                6                 6                    6
Occupant            Ti                Ti                   Si

Point Sym.          3                 3                    3
Wyckoff Not.        6c                6c                   6c

Frac.Coord.
x                   0                 0                    0
y                   0                 0                    0
z                   .14640            .1430                .15768

Distances
1(3)                2.089             2.190                1.830
2(3)                1.874             1.912                1.768

Mean                1.982             2.051                1.799
sigma                .117              .152                 .034

Poly.Vol.           10.001            11.067               7.592
Q.E.                1.0277            1.0310               1.0152
Ang. Var.           86.0              91.4                 52.8

Site Energy        -3959.            -3809.               -4352.

Mineral Data Base Index

GEOL 1010 Syllabus

GEOL 3010 Syllabus

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