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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