Geikielite
| Geikielite | |
|---|---|
|
Crystals of geikielite from the Maxwell quarry, Chelsea, Outaouais, Québec, Canada | |
| General | |
| Category | Oxide mineral |
| Formula (repeating unit) | MgTiO3 |
| Strunz classification | 04.CB.05 |
| Crystal symmetry |
Trigonal rhombohedral H-M symbol: (3) Space group: R3 |
| Unit cell | a = 5.05478(26) Å, c = 13.8992(7) Å; Z=6 |
| Identification | |
| Color | Black, ruby red uncommon; red internal reflections |
| Crystal habit | Tabular prismatic crystals, also as finely granular masses |
| Crystal system | Trigonal |
| Cleavage | Good on {1011} |
| Mohs scale hardness | 5 - 6 |
| Luster | Sub-metallic |
| Streak | Purplish brown |
| Diaphaneity | Opaque to translucent |
| Specific gravity | 3.79 - 4.2 |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 2.310 - 2.350 nε = 1.950 - 1.980 |
| Birefringence | δ = 0.360 - 0.370 |
| Pleochroism | Weak, O = pinkish red, E = brownish to purplish red |
| References | [1][2][3] |
Geikielite is a magnesium titanium oxide mineral with formula: MgTiO3. It is a member of the ilmenite group. It crystallizes in the trigonal system forming typically opaque, black to reddish black crystals.
It was first described in 1892[4] for an occurrence in the Ceylonese gem bearing gravel placers. It was named for Scottish geologist Sir Archibald Geikie (1835–1924).[3] It occurs in metamorphosed impure magnesian limestones, in serpentinite derived from ultramafic rocks, in kimberlites and carbonatites. Associated minerals include rutile, spinel, clinohumite, perovskite, diopside, serpentine, forsterite, brucite, hydrotalcite, chlorite and calcite.[1]
References
- 1 2 Handbook of Mineralogy
- ↑ Geikielite on Mindat.org
- 1 2 Geikielite on Webmineral
- ↑ Fletcher, L. (1892). "Geikielite and Baddeleyite, Two New Mineral Species". Nature 46 (1200): 620. Bibcode:1892Natur..46..620F. doi:10.1038/046620b0.
Further reading
- Ghiorso, Mark S. (1990). "Thermodynamic properties of hematite — Ilmenite — Geikielite solid solutions". Contributions to Mineralogy and Petrology 104 (6): 645. Bibcode:1990CoMP..104..645G. doi:10.1007/BF01167285.
- Reynard, B.; Guyot, F. (1994). "High-temperature properties of geikielite (MgTiO3-ilmenite) from high-temperature high-pressure Raman spectroscopy ? Some implications for MgSiO3-ilmenite". Physics and Chemistry of Minerals 21 (7). Bibcode:1994PCM....21..441R. doi:10.1007/BF00202274.
- Baura-Peña, M. P.; Martínez-Lope, M. J.; García-Clavel, M. E. (1991). "Synthesis of the mineral geikielite MgTiO3". Journal of Materials Science 26 (16): 4341. Bibcode:1991JMatS..26.4341B. doi:10.1007/BF00543648.
- Robie, Richard A.; Haselton, H.T.; Hemingway, Bruce S. (1989). "Heat capacities and entropies at 298.15 K of MgTiO3(geikielite), ZnO (zincite), and ZnCO3 (smithsonite)". The Journal of Chemical Thermodynamics 21 (7): 743. doi:10.1016/0021-9614(89)90058-X.
- Gieré, Reto (1987). "Titanian clinohumite and geikielite in marbles from the Bergell contact aureole". Contributions to Mineralogy and Petrology 96 (4): 496. Bibcode:1987CoMP...96..496G. doi:10.1007/BF01166694.
- Parthasarathy, G. (2007). "Electrical resistivity of nano-crystalline and natural MgTiO3−geikielite at high-pressures up to 8 GPa". Materials Letters 61 (21): 4329. doi:10.1016/j.matlet.2007.01.097.
- Mitchell, Jeremy N.; Yu, Ning; Sickafus, Kurt E.; Nastasi, Michael A.; McClellan, Kenneth J. (1998). "Ion irradiation damage in geikielite (MgTiO3)". Philosophical Magazine A 78 (3): 713. doi:10.1080/01418619808241931.
- http://canmin.geoscienceworld.org/content/9/1/95. Missing or empty
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