Carletonite

{{Short description|Silicate mineral}}

{{Infobox mineral

| name = Carletonite

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| image = Carletonite-20263.jpg

| imagesize = 280px

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| caption = Carletonite, Poudrette quarry, Mont Saint-Hilaire, Montérégie, Quebec, Canada

| category = Phyllosilicate

| formula = KNa₄Ca₄(CO₃)₄Si₈O₁₈(F,OH)·(H₂O)

| IMAsymbol = Cto{{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}}

| molweight =

| strunz = 9.EB.20

| system = Tetragonal

| class = Ditetragonal dipyramidal (4/mmm)
H–M symbol: (4/m 2/m 2/m)

| symmetry = P4/mbm

| unit cell = a = 13.17 Å, c = 16.69 Å; Z = 4

| colour = Colourless, light blue, dark blue, or pink

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| habit = Prismatic crystals, massive

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| cleavage = Perfect on {001}, good on {110}

| fracture = Conchoidal

| tenacity = Brittle

| mohs = 4 - {{frac|4|1|2}}

| lustre = Vitreous

| streak = White

| diaphaneity = Transparent to translucent

| gravity = 2.45

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| opticalprop = Uniaxial (-)

| refractive = n_ω = 1.521 n_ε = 1.517

| birefringence = δ = 0.004

| pleochroism = Weak; O = pale blue; E = pale pinkish brown

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| references = [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Carletonite Mineralienatlas][http://rruff.geo.arizona.edu/doclib/hom/carletonite.pdf Handbook of Mineralogy][http://www.mindat.org/min-898.html Mindat.org][http://webmineral.com/data/Carletonite.shtml Webmineral data]

}}

Carletonite is a rare silicate mineral with formula KNa₄Ca₄(CO₃)₄Si₈O₁₈(F,OH)·(H₂O).

It is a phyllosilicate and a member of the apophyllite group. Its tetragonal crystals are a translucent blue, white, colorless or pink with a vitreous to dull lustre. It has a density of 2.45 and a hardness of 4–4.5.

It was discovered by G.Y Chao and named for the school he attended, Carleton University of Ottawa.[http://www.reciprocalnet.org/recipnet/showsamplebasic.jsp?sampleId=27344235 Carletonite is a rare mineral found only in Mt Saint-Hilaire, Quebec, Canada.] It was first described in 1969 for an occurrence at Mont Saint-Hilaire, Quebec. The type locality at Mont Saint–Hilaire is the only reported occurrence.

It occurs in hornfels and siliceous marble xenoliths within and adjacent to a nepheline syenite intrusion. It occurs in association with quartz, narsarsukite, calcite, fluorite, ancylite, molybdenite, leucosphenite, lorenzenite, galena, albite, pectolite, apophyllite, leifite, microcline and arfvedsonite.