Editing Kainite

{{Short description|Evaporite mineral}}
{{Distinguish|Kainate}}
{{Infobox mineral
| name        = Kainite
| image       = Kainite - Grube Brefeld, Tarthun, Staßfurt, Sachsen-Anhalt.jpg
| imagesize   = 260px
| alt         = 
| caption     = 
| category    = [[Sulfate minerals]]
| formula     = KMg(SO<sub>4</sub>)Cl·3H<sub>2</sub>O
| strunz      = 7.DF.10
| dana        = 
| system      = [[Monoclinic]]
| class       = Prismatic (2/m) <br/><small>(same [[H-M symbol]])</small>
| symmetry    = ''C2/m''
| unit cell   = a = 19.72, b = 16.23 <br/>c = 9.53&nbsp;[Å]; β = 94.92°; Z&nbsp;=&nbsp;16
| color       = Colorless; yellow, brownish, greyish-green, red, violet, blue
| habit       = Crystal aggregates, fibrous, massive
| twinning    = 
| cleavage    = {001}, perfect
| fracture    = Splintery
| tenacity    = Brittle
| mohs        = 2.5–3
| luster      = Vitreous
| streak      = White
| diaphaneity = Transparent
| gravity     = 2.15
| density     = 
| polish      = 
| opticalprop = Biaxial (−)
| refractive  = n<sub>α</sub> = 1.494 n<sub>β</sub> = 1.505 n<sub>γ</sub> = 1.516
| birefringence = δ = 0.022
| pleochroism = Visible: X = violet, Y = blue, Z = yellowish
| 2V          = Measured: 90°
| dispersion  = Weak
| extinction  = 
| length fast/slow =
| fluorescence = 
| absorption  = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| impurities  = 
| alteration  = 
| other       = 
| prop1       = 
| prop1text   = 
| references  = <ref name=HBM>[http://rruff.info/doclib/hom/kainite.pdf The Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-2132.html Mindat.org]</ref><ref name=Webmin>[http://webmineral.com/data/Kainite.shtml#.U6HPHZTMQbg Webmineral.com]</ref>
}}

'''Kainite''' ({{IPAc-en|ˈ|k|aɪ|n|aɪ|t}} or {{IPAc-en|ˈ|k|eɪ|n|aɪ|t}})<ref>{{Cite OED|kainite}}</ref> (KMg(SO<sub>4</sub>)Cl·3H<sub>2</sub>O) is an [[evaporite]] mineral in the class of "Sulfates (selenates, etc.) with additional anions, with H<sub>2</sub>O" according to the [[Nickel–Strunz classification]]. It is a hydrated potassium-magnesium sulfate-chloride, naturally occurring in irregular granular masses or as crystalline coatings in cavities or fissures. This [[mineral]] is dull and soft, and is colored white, yellowish, grey, reddish, or blue to violet. Its name is derived from Greek {{lang|el|καινος}} [kainos] ("(hitherto) unknown"), as it was the first mineral discovered that contained both [[sulfate]] and [[chloride]] as [[anion]]s. Kainite forms [[monoclinic]] crystals.

[[File:Kainite.png|thumb|400px|left|Crystal structure of kainite]]

== Properties ==

Kainite is of bitter taste and soluble in water. On recrystallization [[picromerite]] is deposited from the solution.

== Genesis and occurrence ==

Kainite was discovered in the [[Stassfurt]] salt mines in today's [[Saxony-Anhalt]], [[Germany]] in 1865 by the mine official Schöne and was first described by Carl Friedrich Jacob Zincken.<ref>Zincken, C. (1865): Mittheilung an Prof. H.B. Geinitz vom 18.März 1865 [Über ein neues Mineral, Kainit].- Neues Jahrbuch für Mineralogie, Geologie und Paläontologie, 310.</ref><ref>Zincken, C. (1865): Ueber die Zusammensetzung des Kainits von Leopoldshall bei Stassfurth.- Berg- und hüttenmännische Zeitung 24, 288.</ref>

Kainite is a typical secondary mineral that forms through metamorphosis in marine deposits of [[potassium carbonate]], and is also occasionally formed through resublimation from volcanic vapours. It is often [[paragenesis|accompanied]] by [[anhydrite]], [[carnallite]], [[halite]], and [[kieserite]].

Kainite is only found in comparatively few places,<ref>{{cite web | url = http://www.mindat.org/show.php?id=2132&ld=2#themap | title = Kainite: Localities for Kainite | publisher = Mindat}}</ref> among them in salt mines in central and northern Germany, [[Bad Ischl]] (Austria), on [[Pasquasia]] in [[Sicily]], in [[Whitby]] (UK), and in the Carlsbad Potash District in [[New Mexico]], in volcanic deposits in [[Kamchatka]]<ref>Pekov, Igor V., et al. "New zinc and potassium chlorides from fumaroles of the Tolbachik volcano, Kamchatka, Russia: mineral data and crystal chemistry. II. Flinteite, K2ZnCl4." European Journal of Mineralogy (2015): ejm2459_pap_gsw.</ref> and in [[Iceland]],<ref>Jacobsson et al (1992) Encrustations from Lava Caves on Surtsey, Iceland. A Preliminary Report: Surtsey Research Progress Report X: 73-78 Reykjevik, Iceland.</ref> and in salt lakes in western [[China]]. It has also been identified in [[Gusev Crater]] on [[Mars]].<ref>Rice, M. S., et al. "Silica-rich deposits and hydrated minerals at Gusev Crater, Mars: Vis-NIR spectral characterization and regional mapping." Icarus 205.2 (2010): 375-395.</ref>

It can also be produced from [[Bittern (salt)|bittern]] remaining after removal of table salt from seawater.

== Uses ==

Kainite is used as a source of [[potassium]] and [[magnesium]] compounds, as a [[fertilizer]], and as gritting salt.

==References==
{{Reflist}}

[[Category:Magnesium minerals]]
[[Category:Potassium minerals]]
[[Category:Halide minerals]]
[[Category:Sulfate minerals]]
[[Category:Monoclinic minerals]]
[[Category:Minerals in space group 12]]
[[Category:Evaporite]]
[[Category:Potash]]
[[Category:Trihydrate minerals]]
[[Category:Minerals described in 1865]]


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