# Kochite

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> Source: https://en.wikipedia.org/wiki/Kochite
> Source revision: 1356867724
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{{short description|Rare silicate mineral}}
{{Infobox mineral
| name        = Kochite
| category    = [Sorosilicates](/source/Sorosilicates) <br/>[Rosenbuschite](/source/Rosenbuschite) group
| boxwidth    = 
| boxbgcolor  = 
| image       = 
| imagesize   = 
| caption     = 
| formula     = {{chem2|(Na,Ca)3Ca2(Mn,Ca)ZrTi[(F,O)4(Si2O7)2]}}
| IMAsymbol   = Koh<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   = 
| system      = [Triclinic](/source/Triclinic)
| class       = Pinacoidal ({{overline|1}}) <br/><small>(same [H-M symbol](/source/H-M_symbol))</small>
| symmetry    = ''P''{{overline|1}}
| unit cell   = a = 10.03, b = 11.33 <br/>c = 7.202&nbsp;[Å]; α = 90.19° <br/>β = 100.33°, γ = 111.55°; Z&nbsp;=&nbsp;2
| color       = Colorless to light brown
| habit       = Acicular to lath-shaped prismatic crystals
| twinning    = 
| cleavage    = {100} perfect
| fracture    = Uneven
| tenacity    = Brittle
| mohs  = 5
| luster      = Vitreous
| refractive  = n<sub>α</sub>=1.684, n<sub>β</sub>=1.695, n<sub>γ</sub>=1.718
| opticalprop = Biaxial (+)
| birefringence = 0.0340
| pleochroism = weak, colorless to pale brownish-yellow
| streak      = White
| gravity     = 3.32
| density     = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = Transparent
| other       = 
| references  = <ref name=Mindat>[http://www.mindat.org/min-25598.html Mindat.org]</ref><ref>[http://www.webmineral.com/data/Kochite.shtml Webmineral data]</ref><ref>[http://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Kochite Mineralien Atlas]</ref>
}}

'''Kochite''' is a rare [silicate mineral](/source/silicate_mineral) with chemical formula of {{chem2|(Na,Ca)3Ca2(Mn,Ca)ZrTi[(F,O)4(Si2O7)2]}}<ref name=Mindat/> or double that.<ref>{{cite journal|last1=Jambor|first1=J.L.|last2=Roberts|first2=A.C.|date=January 2004|title=New Mineral Names|url=https://pubs.geoscienceworld.org/msa/ammin/article-abstract/89/1/249/44086/New-Mineral-Names|journal=American Mineralogist|volume=89|issue=1|pages=249–253|url-access=subscription}}</ref> Kochite is a member of the [rosenbuschite](/source/rosenbuschite) group.<ref name=Johnsen2>[http://rruff.geo.arizona.edu/doclib/cm/vol41/CM41_1203.pdf Christiansen, Claes C., Ole Johnsen and Emil Makovicky, ''Crystal Chemistry of the Rosenbuscite Group,'' The Canadian Mineralogist, Vol. 41, pp. 1203-1224 (2003)]</ref>

==Crystallography==
Kochite is [triclinic](/source/triclinic) with angles intersecting at approximately α 90.192°, β 100.192°, γ 111.551°. This mineral belongs to the [space group](/source/space_group) P{{overline|1}} and is centrosymmetric, i.e. contains a center of symmetry.<ref> Mandarino, J.A. (2004) Abstracts of New Mineral Descriptions. The Mineralogy Record, 35, 354-355 </ref> 

It is an [anisotropic](/source/anisotropic) mineral as the light entering the mineral is split into two rays that vibrate at 90° to each other.<ref name=Mindat/>  It is [biaxial](/source/biaxial), meaning it has two [optic axes](/source/Optic_axis) (lines of symmetry). In [plane polarized light](/source/plane_polarized_light), this mineral is colorless to light brown and is [pleochroic](/source/pleochroic). As the stage of the microscope is turned from X to Z the color changes from colorless to a pale brownish-yellow.<ref name=Christiansen>Christiansen, C.C., Gault, R.A., Grice, and J.D., Johnsen, O. (2003) Kochite, a new member of the rosenbuschite group from the Werner Bjerge alkaline complex, East Greenland. European Journal of Mineralogy, 15, 551-554 ]</ref> Kochite is also a [birefringent](/source/Birefringence) mineral, showing bright colors under crossed polarization. Its birefringence is .0340.<ref name=Christiansen/>

==Discovery and occurrence==
Kochite is found in the alkaline igneous complex of [East Greenland](/source/East_Greenland) and is named after [Danish](/source/Danish_people) [geologist](/source/geologist) [Lauge Koch](/source/Lauge_Koch) (1892-1964), a geologist who overturned the previous conception of Greenland's landscapes. It is the [titanium](/source/titanium) – [manganese](/source/manganese) analog of rosenbuschite and occurs in [nepheline syenite](/source/nepheline_syenite) associated with [nepheline](/source/nepheline), [alkali feldspar](/source/alkali_feldspar), and [låvenite](/source/l%C3%A5venite) in the Werner Bjerge alkaline complex along the eastern coast of [Greenland](/source/Greenland).<ref name=Christiansen/>

==References==
{{Reflist}}

Category:Sorosilicates
Category:Triclinic minerals
Category:Minerals in space group 2

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Adapted from the Wikipedia article [Kochite](https://en.wikipedia.org/wiki/Kochite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Kochite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.