The International Mineralogical Association Commission on New Minerals and Mineral Names (CNMMN) adopted the name titanite and "discredited" the name sphene[7] as of 1982,[8] although commonly papers and books initially identify the mineral using both names.[9][10] Sphene was the most commonly used name until the IMA decision, although both were well known.[5] Some authorities[11] think it is less confusing as the word is used to describe any chemical or crystal with oxidized titanium such as the rare earth titanate pyrochlores series[12] and many of the minerals with the perovskite structure.[13] The name sphene continues to be publishable in peer-reviewed scientific literature, e.g. a paper by Hayden et al. was published in early 2008 in the journal Contributions to Mineralogy and Petrology.[11] Sphene persists as the informal name for titanite gemstones.
Physical propertiesEdit
Green titanite crystal cluster from the Tormiq Valley, Haramosh Mountains, Pakistan
Titanite, which is named for its titanium content, occurs as translucent to transparent, reddish brown, gray, yellow, green, or red monocliniccrystals. These crystals are typically sphenoid in habit and are often twinned. Possessing a subadamantine tending to slightly resinous luster, titanite has a hardness of 5.5 and a weak cleavage. Its specific gravity varies between 3.52 and 3.54. Titanite's refractive index is 1.885–1.990 to 1.915–2.050 with a strong birefringence of 0.105 to 0.135 (biaxial positive); under the microscope this leads to a distinctive high relief which combined with the common yellow-brown colour and lozenge-shape cross-section makes the mineral easy to identify. Transparent specimens are noted for their strong trichroism, the three colours presented being dependent on body colour. Owing to the quenching effect of iron, sphene exhibits no fluorescence under ultraviolet light. Some titanite has been found to be metamict, in consequence of structural damage due to radioactive decomposition of the often significant thorium content. When viewed in thin section with a petrographic microscope, pleochroic halos can be observed in minerals surrounding a titanite crystal.
As a gemstone, titanite is usually some shade of chartreuse, but can be brown or black. Hue depends on iron (Fe) content, with low Fe content causing green and yellow colours, and high Fe content causing brown or black hues. Zoning is typical in titanite. It is prized for its exceptional dispersive power (0.051, B to G interval) which exceeds that of diamond.[14] Jewelry use of titanite is limited, both because the stone is uncommon in gem quality and is relatively soft.
Titanite can also be used as a U-Pb geochronometer, specifically in metamorphic terranes.
^ abcdeDana, James Dwight; Ford, William Ebenezer (1915). Dana's Manual of Mineralogy for the Student of Elementary Mineralogy, the Mining Engineer, the Geologist, the Prospector, the Collector, Etc (13 ed.). John Wiley & Sons, Inc. pp. 299–300. Retrieved 2009-07-06.
^Deer, W. A.; Howie, R. A.; Zussman, J. (1966). Introduction to the Rock-Forming Minerals. Longman. pp. 17–20. ISBN0-582-44210-9.
^Nickel, Ernest H.; Nichols, Monte C. (2008-10-17). "IMA/CNMNC List of Mineral Names" (PDF). Material Data, Inc. p. 280. Retrieved 2009-03-14.
^Hey, M. H. (December 1982). "International Mineralogical Association: Commission on New Minerals and Mineral Names". Mineralogical Magazine. 46 (341): 513–514. Bibcode:1982MinM...46..513H. doi:10.1180/minmag.1982.046.341.25. S2CID 140202196.
^Wenk, Hans-Rudolf; Bulakh, Andrei (May 2004). Minerals: Their Constitution and Origin. New York, NY: Cambridge University Press. ISBN978-0-521-52958-7.
^Nesse, William D. (August 2003). Introduction to Optical Mineralogy. New York, NY: Oxford University Press, USA. ISBN978-0-19-514910-4.
^ abHayden, L. A.; Watson, E. B.; Wark, D. A. (2008). "A thermobarometer for sphene (titanite)". Contributions to Mineralogy and Petrology. 155 (4): 529–540. Bibcode:2008CoMP..155..529H. doi:10.1007/s00410-007-0256-y. S2CID 129085138.
^Helean, K. B.; Ushakov, S. V.; Brown, C. E.; Navrotsky, A.; Lian, J.; Ewing, R. C.; Farmer, J. M.; Boatner, L. A. (June 2004). "Formation enthalpies of rare earth titanate pyrochlores". Journal of Solid State Chemistry. 177 (6): 1858–1866. Bibcode:2004JSSCh.177.1858H. doi:10.1016/j.jssc.2004.01.009. S2CID 97381935.
^Freitas, G. F. G.; Nasar, R. S.; Cerqueira, M.; Melo, D. M. A.; Longo, E.; Varela, J. A. (October 2006). "Luminescence in semi-crystalline zirconium titanate doped with lanthanum". Materials Science and Engineering: A. 434 (1–2): 19–22. doi:10.1016/j.msea.2006.07.023.
^"Sphene (Titanite) Value, Price, and Jewelry Information". International Gem Society.
External linksEdit
Madagascar Sphene Properties, Occurrences and Geological data
Wikimedia Commons has media related to Titanite.
October 20, 2023
titanite, sphene, from, greek, sphenos, σφηνώ, meaning, wedge, calcium, titanium, nesosilicate, mineral, catisio5, trace, impurities, iron, aluminium, typically, present, also, commonly, present, rare, earth, metals, including, cerium, yttrium, calcium, partly. Titanite or sphene from the Greek sphenos sfhnw meaning wedge 5 is a calcium titanium nesosilicate mineral CaTiSiO5 Trace impurities of iron and aluminium are typically present Also commonly present are rare earth metals including cerium and yttrium calcium may be partly replaced by thorium 6 Titanite Sphene Titanite crystals on amphibole image width 2 mm GeneralCategorynesosilicateFormula repeating unit CaTiSiO5IMA symbolTtn 1 Strunz classification9 AG 15Crystal systemMonoclinicCrystal classPrismatic 2 m same H M symbol Space groupP21 aUnit cella 7 057 A b 8 707 A c 6 555 A b 113 81 Z 4IdentificationColourReddish brown brown gray black yellow green or red colourlessCrystal habitFlattened wedge shaped crystals also massiveTwinningContact and penetration on 100 lamellar on 221 CleavageDistinct on 110 parting on 221 FractureSub conchoidalMohs scale hardness5 to 5 5LusterSubadamantine tending to slightly resinousStreakReddish whiteDiaphaneityTranslucent to transparentSpecific gravity3 48 to 3 60Optical propertiesBiaxial very high reliefRefractive indexna 1 843 1 950nb 1 870 2 034 ng 1 943 2 110Birefringenced 0 100 0 160PleochroismStrong X nearly colorless Y yellow to green Z red to yellow orange2V angle17 to 40 measured Dispersionr gt v strongOther characteristicsRadioactive may be metamictReferences 2 3 4 5 Titanite crystal model Contents 1 Nomenclature 2 Physical properties 3 Occurrence 4 Uses 5 Image gallery 6 References 7 External linksNomenclature EditThe International Mineralogical Association Commission on New Minerals and Mineral Names CNMMN adopted the name titanite and discredited the name sphene 7 as of 1982 8 although commonly papers and books initially identify the mineral using both names 9 10 Sphene was the most commonly used name until the IMA decision although both were well known 5 Some authorities 11 think it is less confusing as the word is used to describe any chemical or crystal with oxidized titanium such as the rare earth titanate pyrochlores series 12 and many of the minerals with the perovskite structure 13 The name sphene continues to be publishable in peer reviewed scientific literature e g a paper by Hayden et al was published in early 2008 in the journal Contributions to Mineralogy and Petrology 11 Sphene persists as the informal name for titanite gemstones Physical properties Edit nbsp Green titanite crystal cluster from the Tormiq Valley Haramosh Mountains PakistanTitanite which is named for its titanium content occurs as translucent to transparent reddish brown gray yellow green or red monoclinic crystals These crystals are typically sphenoid in habit and are often twinned Possessing a subadamantine tending to slightly resinous luster titanite has a hardness of 5 5 and a weak cleavage Its specific gravity varies between 3 52 and 3 54 Titanite s refractive index is 1 885 1 990 to 1 915 2 050 with a strong birefringence of 0 105 to 0 135 biaxial positive under the microscope this leads to a distinctive high relief which combined with the common yellow brown colour and lozenge shape cross section makes the mineral easy to identify Transparent specimens are noted for their strong trichroism the three colours presented being dependent on body colour Owing to the quenching effect of iron sphene exhibits no fluorescence under ultraviolet light Some titanite has been found to be metamict in consequence of structural damage due to radioactive decomposition of the often significant thorium content When viewed in thin section with a petrographic microscope pleochroic halos can be observed in minerals surrounding a titanite crystal Occurrence EditTitanite occurs as a common accessory mineral in intermediate and felsic igneous rocks and associated pegmatites It also occurs in metamorphic rocks such as gneiss and schists and skarns 2 Source localities include Pakistan Italy Russia China Brazil Tujetsch St Gothard Switzerland 5 Madagascar Tyrol Austria Renfrew County Ontario Canada Sanford Maine Gouverneur Diana Rossie Fine Pitcairn Brewster New York 5 and California in the US Uses EditTitanite is a source of titanium dioxide TiO2 used in pigments As a gemstone titanite is usually some shade of chartreuse but can be brown or black Hue depends on iron Fe content with low Fe content causing green and yellow colours and high Fe content causing brown or black hues Zoning is typical in titanite It is prized for its exceptional dispersive power 0 051 B to G interval which exceeds that of diamond 14 Jewelry use of titanite is limited both because the stone is uncommon in gem quality and is relatively soft Titanite can also be used as a U Pb geochronometer specifically in metamorphic terranes Image gallery Edit nbsp Specimen from the mineral collection of the Naturmuseum Senckenberg in Frankfurt am Main nbsp Titanite crystal that is totally gemmy and transparent with a light olive green color perched on matrix of calcite and epidote nbsp Bright green twinned crystal of titanite with adularia and minor clinochlore on matrix nbsp Olive green titanite spear point set in matrix from Pakistan nbsp Green titanite crystal perched right at the top of a column of gray chlorite included crystals nbsp Yellow green titanite twinned crystal perched vertically on the matrixReferences Edit 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 a b Handbook of Mineralogy PDF Webmineral data Mindat a b c d e Dana James Dwight Ford William Ebenezer 1915 Dana s Manual of Mineralogy for the Student of Elementary Mineralogy the Mining Engineer the Geologist the Prospector the Collector Etc 13 ed John Wiley amp Sons Inc pp 299 300 Retrieved 2009 07 06 Deer W A Howie R A Zussman J 1966 Introduction to the Rock Forming Minerals Longman pp 17 20 ISBN 0 582 44210 9 Nickel Ernest H Nichols Monte C 2008 10 17 IMA CNMNC List of Mineral Names PDF Material Data Inc p 280 Retrieved 2009 03 14 Hey M H December 1982 International Mineralogical Association Commission on New Minerals and Mineral Names Mineralogical Magazine 46 341 513 514 Bibcode 1982MinM 46 513H doi 10 1180 minmag 1982 046 341 25 S2CID 140202196 Wenk Hans Rudolf Bulakh Andrei May 2004 Minerals Their Constitution and Origin New York NY Cambridge University Press ISBN 978 0 521 52958 7 Nesse William D August 2003 Introduction to Optical Mineralogy New York NY Oxford University Press USA ISBN 978 0 19 514910 4 a b Hayden L A Watson E B Wark D A 2008 A thermobarometer for sphene titanite Contributions to Mineralogy and Petrology 155 4 529 540 Bibcode 2008CoMP 155 529H doi 10 1007 s00410 007 0256 y S2CID 129085138 Helean K B Ushakov S V Brown C E Navrotsky A Lian J Ewing R C Farmer J M Boatner L A June 2004 Formation enthalpies of rare earth titanate pyrochlores Journal of Solid State Chemistry 177 6 1858 1866 Bibcode 2004JSSCh 177 1858H doi 10 1016 j jssc 2004 01 009 S2CID 97381935 Freitas G F G Nasar R S Cerqueira M Melo D M A Longo E Varela J A October 2006 Luminescence in semi crystalline zirconium titanate doped with lanthanum Materials Science and Engineering A 434 1 2 19 22 doi 10 1016 j msea 2006 07 023 Sphene Titanite Value Price and Jewelry Information International Gem Society External links EditMadagascar Sphene Properties Occurrences and Geological data nbsp Wikimedia Commons has media related to Titanite Retrieved from https en wikipedia org w index php title Titanite amp oldid 1174534217, wikipedia, wiki, book, books, library,
