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Geikielite
A valid IMA mineral species - grandfathered
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About Geikielite
Sir Archibald Geikie, Director General, British Geological Survey.
Formula:
MgTiO3
Colour:
Black, red, brownish black
Lustre:
Sub-Metallic
Hardness:
5 - 6
Specific Gravity:
3.79 - 4.2
Crystal System:
Trigonal
Member of:
Name:
For Sir Archibald Geikie (Edinburgh 28 December 1835 – Haslemere, Surrey 10 November 1924), Professor of Geology and Mineralogy in the University of Edinburgh, Scotland, and Director-General of the Geological Survey of Great Britain and Ireland.
Ilmenite Group. Geikielite-Ilmenite Series. The magnesium analogue of Ilmenite, Pyrophanite, and Ecandrewsite. The titanium analogue of Akimotoite.
May be confused with Hematite.
May be confused with Hematite.
Unique Identifiers
Mindat ID:
1670
Long-form identifier:
mindat:1:1:1670:0
IMA Classification of Geikielite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
MgTi4+O3
First published:
1892
Classification of Geikielite
4.CB.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
C : Metal: Oxygen = 2: 3,3: 5, and similar
B : With medium-sized cations
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
C : Metal: Oxygen = 2: 3,3: 5, and similar
B : With medium-sized cations
4.3.5.2
4 : SIMPLE OXIDES
3 : A2X3
4 : SIMPLE OXIDES
3 : A2X3
7.9.5
7 : Oxides and Hydroxides
9 : Oxides of Ti
7 : Oxides and Hydroxides
9 : Oxides of Ti
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Gk | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Gk | Whitney & Evans (2010) | Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371 |
| Gkl | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Geikielite
Sub-Metallic
Transparency:
Translucent, Opaque
Colour:
Black, red, brownish black
Streak:
Purple brown
Hardness:
5 - 6 on Mohs scale
Cleavage:
Distinct/Good
On {1011}
On {1011}
Fracture:
Conchoidal, Sub-Conchoidal
Density:
3.79 - 4.2 g/cm3 (Measured) 3.895 g/cm3 (Calculated)
Optical Data of Geikielite
Type:
Uniaxial (-)
RI values:
nω = 2.31 - 2.35 nε = 1.95 - 1.98
Max. Birefringence:
δ = 0.360 - 0.370
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Anisotropism:
Strong
Colour in reflected light:
Gray
Internal Reflections:
Red
Pleochroism:
Weak
Comments:
O = Pinkish red
E = Brownish to purplish red
E = Brownish to purplish red
Chemistry of Geikielite
Mindat Formula:
MgTiO3
Element Weights:
Elements listed:
Common Impurities:
Fe,Cr,Mn,Ca
Crystallography of Geikielite
Crystal System:
Trigonal
Class (H-M):
3 - Pyramidal
Space Group:
R3
Cell Parameters:
a = 5.05478(26) Å, c = 13.8992(7) Å
Ratio:
a:c = 1 : 2.75
Unit Cell V:
307.56 ų (Calculated from Unit Cell)
Z:
6
Morphology:
Tabular to prismatic crystals.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0006108 | Geikielite | Liferovich R P, Mitchell R H (2006) The pyrophanite-geikielite solid-solution series: crystal structures of the Mn1-xMgxTiO3 series (0 < x < 0.7) The Canadian Mineralogist 44 1099-1107 |  | 2006 | synthetic | 0 | 293 |
| 0006107 | Geikielite | Liferovich R P, Mitchell R H (2006) The pyrophanite-geikielite solid-solution series: crystal structures of the Mn1-xMgxTiO3 series (0 < x < 0.7) The Canadian Mineralogist 44 1099-1107 | | 2006 | synthetic | 0 | 293 |
| 0009834 | Geikielite | Wechsler B A, Von Dreele R B (1989) Structure refinements of Mg2TiO4, MgTiO3 and MgTi2O5 by time-of-flight neutron powder diffraction Acta Crystallographica B45 542-549 |  | 1989 | synthetic | 0 | 293 |
| 0008981 | Geikielite | Liferovich R P, Mitchell R H (2005) Rhombohedral ilmenite group nickel titanates with Zn, Mg, and Mn: synthesis and crystal structures Physics and Chemistry of Minerals 32 442-449 | 2005 | 0 | 293 | ||
| 0008980 | Geikielite | Liferovich R P, Mitchell R H (2005) Rhombohedral ilmenite group nickel titanates with Zn, Mg, and Mn: synthesis and crystal structures Physics and Chemistry of Minerals 32 442-449 | 2005 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.722 Å | (100) |
| 2.218 Å | (70) |
| 2.527 Å | (55) |
| 1.708 Å | (55) |
| 3.703 Å | (45) |
| 1.852 Å | (40) |
| 1.4592 Å | (40) |
Comments:
Synthetic. Data from Swanson et al. (1955).
San Vito Quarry, San Vito, Ercolano, Metropolitan City of Naples, Campania, Italy