Vishnevite

{{short description|Feldspathoid mineral in the cancrinite subgroup}}

{{Infobox mineral

| name = Vishnevite

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| image = Vishnevite - sulfate cancrinite w- orthoclase and melanite Hydrous sodium calcium potassium aluminum silicate sulfate and carbonate Loch Borrolan Sutherland Scotland 1650.jpg

| imagesize = 260px

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| caption = Vishnevite from Scotland

| category = Tectosilicate minerals, feldspathoid group, cancrinite group

| formula = (Na,Ca,K)₆(Si,Al)₁₂O₂₄[(SO₄),(CO₃),Cl₂]_2-4·nH₂O

| IMAsymbol = Vhn{{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}}

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| strunz = 9.FB.05

| system = Hexagonal

| class = Pyramidal (6)
H-M symbol: (6)

| symmetry = P6₃

| unit cell = a = 12.7228(3)
c = 5.198(3) [Å]; Z = 1

| color = Colorless, light blue, orange-yellow, white

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| cleavage = Perfect

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| mohs = 5 - 6

| luster = Vitreous, pearly

| streak = White

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| opticalprop = Uniaxial (-)

| refractive = n_ω = 1.490 - 1.507 n_ε = 1.488 - 1.495

| birefringence = δ = 0.002 - 0.012

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Vishnevite, or sulfatic cancrinite, is a mineral of the cancrinite group with the chemical formula (Na, Ca, K)₆(Si, Al)₁₂O₂₄[(SO₄),(CO₃), Cl₂]_2-4·nH₂O. It has hexagonal crystals.Fleischer, Michael & Mandarino, Joseph, "Glossary of Mineral Species", The Mineralogical Record, 1991[http://www.webmineral.com/data/Vishnevite.shtml Webmineral data]