Geikielite

Magnesium titanium oxide mineral
(repeating unit)MgTiO3IMA symbolGk[1]Strunz classification4.CB.05Crystal systemTrigonalCrystal classRhombohedral (3)
(same H-M symbol)Space groupR3Unit cella = 5.05478(26) Å
c = 13.8992(7) Å; Z = 6IdentificationColorBlack, ruby red uncommon; red internal reflectionsCrystal habitTabular prismatic crystals, also as finely granular massesCleavageGood on {1011}Mohs scale hardness5 - 6LusterSub-metallicStreakPurplish brownDiaphaneityOpaque to translucentSpecific gravity3.79 - 4.2Optical propertiesUniaxial (-)Refractive indexnω = 2.310 - 2.350 nε = 1.950 - 1.980Birefringenceδ = 0.360 - 0.370PleochroismWeak, O = pinkish red, E = brownish to purplish redReferences[2][3][4]

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[5] for an occurrence in the Ceylonese gem bearing gravel placers. It was named for Scottish geologist Sir Archibald Geikie (1835–1924).[4] 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.[2]

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b Handbook of Mineralogy
  3. ^ Geikielite on Mindat.org
  4. ^ a b Geikielite on Webmineral
  5. ^ Fletcher, L. (1892). "Geikielite and Baddeleyite, Two New Mineral Species". Nature. 46 (1200): 620–621. 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): 645–667. Bibcode:1990CoMP..104..645G. doi:10.1007/BF01167285. S2CID 98522254.
  • 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): 441. Bibcode:1994PCM....21..441R. doi:10.1007/BF00202274. S2CID 96095190.
  • 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. S2CID 94170430.
  • 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): 496–502. Bibcode:1987CoMP...96..496G. doi:10.1007/BF01166694. S2CID 86861792.
  • Parthasarathy, G. (2007). "Electrical resistivity of nano-crystalline and natural MgTiO3−geikielite at high-pressures up to 8 GPa". Materials Letters. 61 (21): 4329–4331. 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. Bibcode:1998PMagA..78..713M. doi:10.1080/01418619808241931.
  • Chao, G. Y.; Hounslow, A. W. (June 1967). "Geikielite; a new Canadian occurrence". The Canadian Mineralogist. 9 (1): 95–100.

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