Banalsite

{{Short description|Rare barium feldspar mineral}} {{infobox mineral | name = Banalsite | category = Tectosilicate minerals | group = Feldspar group | image =Banalsite.jpg | alt = | caption = Banalsite from Sweden (brown) on matrix | boxbgcolor = #231709 | boxtextcolor = white | formula = BaNa₂Al₄Si₄O₁₆ |IMAsymbol=Bns<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> | IMAstatus = Grandfathered (1944) | molweight = | strunz = 9.FA.60 | dana = 76.1.6.1 | system = Orthorhombic | class = Rhombic pyramidal (mm2) | symmetry = Iba2 (no. 45) | unit cell = a = 8.496(2)&nbsp;Å, <br/>b = 9.983(2)&nbsp;Å, <br/>c = 16.755(3)&nbsp;Å; Z&nbsp;=&nbsp;4 | color = White, brown | colour = | habit = Rarely showing traces of crystal faces; coarsely crystalline to compact, massive | twinning = | cleavage = Good on {110} and {001} | fracture = | tenacity = | mohs = 6.5 | luster = Vitreous, pearly on cleavage | streak = White | diaphaneity = Translucent to transparent | gravity = 3.065 | density = | polish = | opticalprop = Biaxial (+) | refractive = n_α = 1.570 n_β = 1.571 n_γ = 1.578 | birefringence = | pleochroism = | 2V = Measured: 41°, Calculated: 52° | dispersion = | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = | alteration = | references = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Banalsite Mineralienatlas]</ref><ref name=Handbook>http://rruff.geo.arizona.edu/doclib/hom/banalsite.pdf Handbook of Mineralogy</ref><ref name=Mindat>http://www.mindat.org/min-504.html Mindat.org</ref><ref name=Webmin>http://www.webmineral.com/data/Banalsite.shtml Webmineral data</ref> }} '''Banalsite''' is a rare barium, sodium aluminium silicate mineral with formula: BaNa₂Al₄Si₄O₁₆. Banalsite is a tectosilicate of the feldspar group.

Banalsite and its strontium analogue, stronalsite (SrNa₂Al₄Si₄O₁₆), constitute a complete solid solution series.<ref>[http://rruff.info/uploads/CM44_533.pdf Liferovich, Ruslan P., et al., ''The Crystal Structure of Stronalsite and a Redetermination of the Structure of Banalsite,'' The Canadian Mineralogist, Vol. 44, pp. 533-546 (2006)]</ref> In addition limited solid solution with calcium exists between these and lisetite: CaNa₂Al₄Si₄O₁₆.<ref name=Liferovich2>[http://rruff.info/uploads/CM44_929.pdf Liferovich, Ruslan P., et al., ''Paragenesis and Composition of Banalsite, Stronalsite, and Their Solid Solution in Nepheline Syenite and Ultramafic Alkaline Rocks,'' The Canadian Mineralogist, Vol. 44, pp. 929-942 (2006)]</ref>

It was first described in 1944 for an occurrence in the Benallt Mine, Rhiw, Llanfaelrhys, Lleyn Peninsula, Gwynedd (Caernarvonshire), Wales.<ref name=Mindat/> The name is derived from the chemical symbols of its composition. It has also been reported from Långban, Värmland, Sweden and from the Kalahari manganese field, Cape Province, South Africa.<ref name=Handbook/> It has recently been reported from the nepheline syenites of the Zhidoy massif, Eastern Sayan, Siberia, Russia; the Prairie Lake complex of alkaline rocks and carbonatites, Superior Alkaline Province, northwestern Ontario, Canada; the Pilansberg peralkaline complex, South Africa; the Sakharjok alkaline complex in the Kola Alkaline Province, Kola Peninsula of northwestern Russia (the Gremyakha–Vyrmes peralkaline complex, and the Turiy Mys complex of ultramafic–alkaline rocks and carbonatites).<ref name=Liferovich2/>

==References== {{Reflist}}

Category:Feldspar group Category:Orthorhombic minerals Category:Minerals in space group 45 Category:Barium minerals Category:Sodium minerals Category:Aluminium minerals Category:Aluminosilicates

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