# Kurnakovite

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> Source: https://en.wikipedia.org/wiki/Kurnakovite
> Source revision: 1309771740
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{{short description|Hydrated borate of magnesium}}
{{Infobox mineral
| name        = Kurnakovite
| boxwidth    =
| image       = Kurnakovite-mrz200a.jpg
| alt         =
| caption     = Kurnakovite from [Boron, California](/source/Boron%2C_California)
| category    = [Nesoborates](/source/Nesoborates)
| formula     = MgB<sub>3</sub>O<sub>3</sub>(OH)<sub>5</sub>·5H<sub>2</sub>O
| IMAsymbol   = Kko<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      = 6.CA.20
| dana        =
| 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 = 8.3479(1) <br/>b = 10.6068(1) <br/>c = 6.4447(1)&nbsp;[Å] <br/>α = 98.846°, β = 108.981° <br/>γ = 105.581°; Z&nbsp;=&nbsp;2
| color       = White; colorless in transmitted light
| colour      = 
| habit       = Aggregates of prismatic crystals
| twinning    = Twinning uncommon
| cleavage    = Poor to indistinct on {010}
| fracture    =
| tenacity    =
| mohs        = {{frac|2|1|2}} – 3
| luster      = Vitreous
| streak      = White
| diaphaneity = Transparent to translucent
| gravity     = 1.847 – 1.852
| density     = 
| polish      =
| opticalprop = Biaxial (-)
| refractive  = n<sub>α</sub> = 1.488 – 1.491 n<sub>β</sub> = 1.508 – 1.510 n<sub>γ</sub> = 1.515 – 1.525
| birefringence = δ = 0.027 – 0.034
| pleochroism =
| 2V          = Measured: 60° to 80°
| dispersion  =
| extinction  =
| length fast/slow =
| fluorescence =
| absorption  =
| melt        =
| fusibility  =
| diagnostic  =
| solubility  =
| impurities  =
| alteration  =
| other       =
| prop1       =
| prop1text   =
| references  = <ref name=HBM>[http://www.handbookofmineralogy.com/pdfs/kurnakovite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/show.php?id=2295&ld=1 Mindat.org]</ref><ref name=Webmin>[http://www.webmineral.com/data/Kurnakovite.shtml Webmineral data]</ref>
}}

'''Kurnakovite''' is a hydrated [borate](/source/borate_mineral) of [magnesium](/source/magnesium) with the chemical composition MgB<sub>3</sub>O<sub>3</sub>(OH)<sub>5</sub>·5H<sub>2</sub>O. It is a member of the [inderite](/source/inderite) group and is a [triclinic](/source/triclinic) [dimorph](/source/polymorphism_(materials_science)) of the [monoclinic](/source/monoclinic) inderite.<ref name=Mindat/>

==Discovery and occurrence==
Kurnakovite, was first described by Godlevsky in 1940 for an occurrence in the [Inder lake](/source/Inder_(lake)) borate deposits in [Atyrau Province](/source/Atyrau_Province), [Kazakhstan](/source/Kazakhstan), and is named for Russian mineralogist and chemist [Nikolai Semenovich Kurnakov](/source/Nikolai_Semenovich_Kurnakov) (1860–1941).<ref name=HBM/>

In addition to the [type locality](/source/Type_locality_(geology)) in Kazakhstan, kurakovite has also been reported from the Zhacang-Caka brine lake, [Tibet](/source/Tibet); the Kirka borate deposit, [Kiitahya Province](/source/Kiitahya_Province), [Turkey](/source/Turkey);  the Kramer borate deposit, Boron, [Kern County, California](/source/Kern_County%2C_California); [Death Valley National Park](/source/Death_Valley_National_Park), [Inyo County, California](/source/Inyo_County%2C_California); and the Tincalayu borax deposit, Salar del Hombre Muerto, [Salta Province](/source/Salta_Province), [Argentina](/source/Argentina).<ref name=HBM/><ref name=Mindat/>

==Properties==
Kurnakovite has [triclinic](/source/triclinic) – pinacodial crystallography. It forms as rough, prismatic [crystals](/source/crystals), typically in dense aggregates. Kurnakovite has distinct [cleavage](/source/Cleavage_(crystal)) and a [conchoidal fracture](/source/conchoidal_fracture). Its [tenacity](/source/Tenacity_(mineralogy)) is [brittle](/source/brittle) and it ranges between 2.5 – 3 on the [Mohs hardness](/source/Mohs_hardness) scale. It is not soluble in water, though it will start dissolving in warm acid. Kurnakovite is usually colorless or white and either transparent or translucent. It has a vitreous, pearly [luster](/source/Lustre_(mineralogy)) and a [refractive index](/source/refractive_index) of between 1.488 – 1.525.<ref name=HBM/><ref name=Mindat/><ref name=Webmin/>

==References==
{{Reflist}}

{{Commons category}}

Category:Magnesium minerals
Category:Nesoborates
Category:Triclinic minerals
Category:Minerals in space group 2

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