Editing Baddeleyite

{{Infobox mineral
| name        = Baddeleyite
| category    = Oxide mineral
| boxwidth    = 
| boxbgcolor  = 
| image       = Baddeleyite-md12a.jpg
| imagesize   = 
| alt         = 
| caption     = Baddeleyite from Phalaborwa, South Africa
| formula     = [[Zirconium dioxide]] (ZrO<sub>2</sub>)
|IMAsymbol=Bdy<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref>
| molweight   = 
| strunz      = 4.DE.35
| dana        = 04.04.14.01
| system      = [[Monoclinic]] 
| class       = Prismatic (2/m) <br/><small>(same [[H-M symbol]])</small>
| symmetry    = ''P''2<sub>1</sub>/c
| unit cell   = a = 5.1505&nbsp;Å, <br/>b = 5.2116&nbsp;Å, <br/>c = 5.3173&nbsp;Å, β = 99.23°; Z&nbsp;=&nbsp;4
| color       = Colorless to yellow, blue, green, greenish or reddish brown, brown, iron-black
| colour      = 
| habit       = Tabular prismatic, radially fibrous in botryoidal masses
| twinning    = Ubiquitous polysynthetic on {100} and {110}
| cleavage    = {001} distinct
| fracture    = Irregular uneven to subconchoidal
| tenacity    = Brittle
| mohs        = 6.5
| luster      = Greasy to vitreous
| streak      = White
| diaphaneity = Transparent to translucent
| gravity     = 5.5–6
| density     = 
| polish      = 
| opticalprop = Biaxial (–)
| refractive  = n<sub>α</sub> = 2.130<br/> n<sub>β</sub> = 2.190<br/> n<sub>γ</sub> = 2.200
| birefringence = δ = 0.070
| pleochroism = X = yellow, reddish brown, oil-green; Y = oil-green, reddish brown; Z = brown, light brown
| 2V          = Measured: 30° to 31°
| dispersion  = r > v, rather strong
| extinction  = 
| length fast/slow =
| fluorescence= 
| absorption  =
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| other       = Blue-green cathodoluminescence
| alteration  = 
| references  = <ref name=Handbook>{{cite book|editor1=Anthony, John W. |editor2=Bideaux, Richard A. |editor3=Bladh, Kenneth W. |editor4=Nichols, Monte C. |title= Handbook of Mineralogy|publisher= Mineralogical Society of America|place= Chantilly, VA, US|url=http://rruff.geo.arizona.edu/doclib/hom/baddeleyite.pdf|chapter=Baddeleyite |date=1990 |access-date=December 5, 2011|isbn=0962209724 |volume=III (Halides, Hydroxides, Oxides)}}</ref><ref>[http://www.webmineral.com/data/Baddeleyite.shtml Baddeleyite]. Webmineral</ref><ref name=Mindat>[http://www.mindat.org/min-480.html Baddeleyite]. Mindat</ref>
}}

'''Baddeleyite''' is a rare [[zirconium]] [[oxide mineral]] (ZrO<sub>2</sub> or [[zirconia]]), occurring in a variety of [[monoclinic]] prismatic crystal forms. It is transparent to translucent, has high [[Index of refraction|indices of refraction]], and ranges from colorless to yellow, green, and dark brown. See etymology [[Baddeleyite#Origin of the name|below]].

Baddeleyite is a [[refractory]] mineral, with a [[melting point]] of 2700&nbsp;°C. [[Hafnium]] is a substituting ''impurity'' and may be present in quantities ranging from 0.1 to several percent.

It can be found in [[igneous]] rocks containing [[potassium feldspar]] and [[plagioclase]]. Baddeleyite is commonly not found with [[zircon]] (ZrSiO<sub>4</sub>), because it forms in silica-undersaturated rocks, such as [[mafic]] rocks. This is because, when silica is free in the system (silica-saturated/oversaturated), zircon is the dominating phase, not baddeleyite. It belongs to the [[Monoclinic crystal system|monoclinic-prismatic class]], of the P2<sub>1</sub>/c [[crystal system]]. It has been used for [[geochronology]].<ref name= Bayanova >{{cite journal|author=Bayanova, T.B.|doi=10.1134/S0869591106020032|title=Baddeleyite: A promising geochronometer for alkaline and basic magmatism|year=2006|journal=Petrology|volume=14|issue=2|pages=187–200|bibcode=2006Petro..14..187B |s2cid=129079168}}</ref>

==Geologic occurrence==

Baddeleyite was first found in [[Sri Lanka]] in 1892. It can be found in numerous terrestrial and extraterrestrial rocks. Some of these terrestrial rocks are [[carbonatite]], [[kimberlite]], alkaline [[syenite]], some rocks of [[Layered intrusion|layered mafic intrusion]]s, [[diabase]] [[Dike (geology)|dikes]], [[gabbro]]id [[Sill (geology)|sills]] and [[anorthosite]].<ref name= Bayanova/>  Some examples of extraterrestrial rocks are [[tektite]]s, [[meteorite]]s and lunar [[basalt]]. Studies have shown that zircon and baddeleyite can be recovered from some anorthositic rocks in [[Proterozoic]] anorthosite complexes.<ref name = Scoates>{{cite journal|author1=Scoates, James |author2=Kevin Chamberlain |name-list-style=amp |title=Baddeleyite (ZrOr) and zircon (ZrSiO) from anorthositic rocks of the Laramie anorthosite complex, Wyoming: Petrologic consequences and U-Pb ages|journal= American Mineralogist|year =1995|volume=80|issue=11–12 |pages=1317–1327|url=http://www.minsocam.org/msa/ammin/toc/Articles_Free/1995/Scoates_p1317-1327_95.pdf|bibcode=1995AmMin..80.1317S|doi=10.2138/am-1995-11-1222|s2cid=46901671 }}</ref>  Places where these Proterozoic anorthosite complexes can be found are: the Laramie Anorthosite Complex in Wyoming, the Nain and Grenville provinces of Canada, the Vico Volcanic Complex in Italy,<ref name=Bellatreccia>{{cite journal|author=Bellatreccia, Fabio|author2=Giancarlo Della Ventura|author3=Gian Carlo Parodi|author4=Terry Williams|name-list-style=amp |doi=10.1007/BF02904453 |url=http://www.lincei.it/pubblicazioni/rendicontiFMN/rol/pdf/S1998-01-02.pdf |title=Baddeleyite from the vico volcanic complex, latium Italy |year=1998 |journal=Rendiconti Lincei |volume=9 |issue=1 |pages=27–33 |bibcode=1998RLSFN...9...27B |s2cid=126680669|url-status=dead |archive-url=https://web.archive.org/web/20071212194406/http://www.lincei.it/pubblicazioni/rendicontiFMN/rol/pdf/S1998-01-02.pdf |archive-date=2007-12-12 }}</ref> and [[Minas Gerais]] and [[Jacupiranga]], [[São Paulo]], [[Brazil]]. Baddeleyite forms in igneous rocks low in silica, it can be found in rocks containing potassium feldspar and plagioclase. It has been observed in [[thin section]] that baddeleyite forms within plagioclase grains. Associated minerals include [[ilmenite]], [[zirkelite]], [[apatite]], [[magnetite]], [[perovskite]], [[fluorite]], [[nepheline]], [[pyrochlore]] and [[allanite]].<ref name=Handbook/>

Because of their refractory nature and stability under diverse conditions, baddeleyite grains, along with [[zircon]], are used for [[Radiometric dating#Uranium-lead dating method|uranium-lead]] [[Radiometric dating|radiometric age]] determinations.
[[File:BaddeleyiteStructure.png|thumb|left|150px|Crystal structure of baddeleyite<ref>{{cite journal|last1=Drabińska|first1=A.|last2=Grodecki|first2=K.|last3=Strupiński|first3=W.|last4=Bożek|first4=R.|last5=Korona|first5=K. P.|last6=Wysmołek|first6=A.|last7=Stępniewski|first7=R.|last8=Baranowski|first8=J. M.|title=Growth kinetics of epitaxial graphene on SiC substrates|journal=Physical Review B|volume=81|pages=245410|year=2010|doi=10.1103/PhysRevB.81.245410|issue=24|bibcode = 2010PhRvB..81x5410D }}</ref>]]

==Structure==
There has been some dispute in the structure of baddeleyite.  Originally, the mineral was assigned to the 8-fold coordination by Naray Szabo. This structure was ruled out due to the inaccuracy of the data used to establish it.

Baddeleyite has the group symmetry P2<sub>1</sub>/c with four ZrO<sub>2</sub> in the [[unit cell]]. It has unit cell dimensions of:
a = 5.169  b = 5.232  c = 5.341 [[Angstrom|Å]] (all ± 0.008 Å), β =  99˚15ˊ ± 10ˊ.

The coordination number for ZrO<sub>2</sub> has been found to be 7. The mineral has two types of separations. The first being the seven shortest Zr-O, ranging from 2.04 to 2.26 Å, and the second Zr-O separation is 3.77 Å.  Because of this, the coordination of baddeleyite was determined to be sevenfold. Baddeleyite's structure is a combination of tetrahedrally coordinated oxide ions parallel to (100) with triangular coordinated oxide ions. This explains baddeleyite's tendency to twin along the (100) planes. It has been observed that baddeleyite without twinning is extremely rare.<ref name= McCullough >{{cite journal|author1=McCullough, J. D.  |author2=Trueblood, K. N. |name-list-style=amp |doi=10.1107/S0365110X59001530|title=The crystal structure of baddeleyite (monoclinic ZrO2)|year=1959|journal=Acta Crystallographica|volume=12|issue=7|pages=507|bibcode=1959AcCry..12..507M }}</ref>

==Composition==
Baddeleyite belongs to the oxide group, having a composition of [[Zirconium dioxide|ZrO<sub>2</sub>]]. Similar minerals belonging to the same group are the rutile group: [[rutile]] (TiO<sub>2</sub>), [[pyrolusite]] (MnO<sub>2</sub>), [[cassiterite]] (SnO<sub>2</sub>), [[uraninite]] (UO<sub>2</sub>) and [[thorianite]] (ThO<sub>2</sub>).  Baddeleyite is chemically homogeneous, but it may contain impurities such as Ti, Hf, and Fe.<ref name= Lumpkin >{{cite journal|author=Lumpkin, G.R.|doi=10.1016/S0022-3115(99)00066-5|title=Physical and chemical characteristics of baddeleyite (monoclinic zirconia) in natural environments: An overview and case study|year=1999|journal=Journal of Nuclear Materials|volume=274|issue=1–2|pages=206–217|bibcode = 1999JNuM..274..206L }}</ref>  Higher concentrations of Ti and Fe are restricted to [[mafic]]-[[ultramafic rocks]].

==Physical properties==
Baddeleyite is black in color with a submetallic lustre. It has a 6.5 hardness, and a brownish-white streak. Baddeleyite can also be brown, brownish black, green, and greenish brown. Its streak is white, or brownish white. It has a distinct cleavage along {001} and tends to twin along (100). It belongs to the [[Monoclinic crystal system|monoclinic system]] and is part of the P21/c group.<ref name= Fletcher>{{cite journal|author=Fletcher, L. |title=On Baddeleyite (native zirconia), a new Mineral, from Rakwana, Ceylon|journal= Mineralogy Magazine and Journal of the Mineralogical Society|year=1892|pages= 149–161|url=http://www.minersoc.org/pages/Archive-MM/Volume_10/10-46-148.pdf}}</ref>

==Origin of the name==
It was named for Joseph Baddeley. The mineral was discovered in [[Rakwana]], [[Sri Lanka|Ceylon]] (now [[Sri Lanka]]). Baddeley was a superintendent of a railroad project in Rakwana. As recounted by J.J.H. Teall – director of the British Geological Survey in the early 1900s – baddeleyite was discovered consequent to the discovery of [[geikielite]].

Baddeley sent specimens of several pebbles from the [[Rakwana]] railroad excavations to the [[Geological Museum|Museum of Practical Geology in London]], where a Mr.&nbsp;Pringle examined them and attempted to classify them.
Pringle was unable to assign the specimens to a known mineral species and submitted them to Teall. After analyzing the specimens, Teall concluded that the mineral was mainly composed of [[titanic acid]] and [[Magnesium oxide|magnesia]], with an incidental mixture of [[iron(II) oxide|protoxide of iron]]. Geikielite has the composition of {{chem2|MgTiO3}}.
Teall and Pringle decided to name the new mineral ''geikielite'', naming it after Sir&nbsp;[[Archibald Geikie]], then the Director General of the Geological Survey.

Baddeley sent more specimens to Teall, in order to provide an exemplary specimen for display at the Museum of Practical Geology. While trying to find the specimens, Teall noticed that one of them was different from the rest: This new mineral was black in color, with a submetallic lustre, and a [[Mohs hardness|hardness]] of 6.5&nbsp;. After analyzing it, the odd mineral was determined to not be {{chem2|MgTiO3}} (geikielite), but instead {{chem2|ZrO2}}. Teall proposed mineral name ''baddeleyite'', after Joseph Baddeley, to honor the man who brought the two new minerals to notice.<ref name="Fletcher"/>

==See also==
*[[List of minerals]]
*[[List of minerals named after people]]

==References==
{{reflist|25em}}

==External links==
*[http://www.minweb.co.uk/oxides/baddeleyite.html Minweb with ''chime'' structure] {{Webarchive|url=https://web.archive.org/web/20110927153639/http://www.minweb.co.uk/oxides/baddeleyite.html |date=2011-09-27 }}
*[http://www.uwrf.edu/~wc01//baddeleyite.htm Bill Cordura, University of Wisconsin] {{Webarchive|url=https://web.archive.org/web/20071112023006/http://www.uwrf.edu/~wc01/baddeleyite.htm |date=2007-11-12 }}
*[http://news.bbc.co.uk/1/hi/sci/tech/8080126.stm Early rocks to reveal their ages, BBC News]

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[[Category:Zirconium minerals]]
[[Category:Oxide minerals]]
[[Category:Monoclinic minerals]]
[[Category:Minerals in space group 14]]