carletonite

{{Infobox mineral | name = Carletonite | boxwidth = | boxbgcolor = | image = Carletonite-20263.jpg | imagesize = 280px | alt = | caption = Carletonite, Poudrette quarry, Mont Saint-Hilaire, Montérégie, Quebec, Canada | category = Phyllosilicate minerals | formula = KNa4Ca4(CO3)4Si8O18(F,OH)·(H2O) | IMAsymbol = Cto | 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 | color = | habit = Prismatic crystals, massive | twinning = | cleavage = Perfect on {001}, good on {110} | fracture = Conchoidal | tenacity = Brittle | mohs = 4 - | lustre = Vitreous | streak = White | diaphaneity = Transparent to translucent | gravity = 2.45 | density = | polish = | opticalprop = Uniaxial (-) | refractive = nω = 1.521 nε = 1.517 | birefringence = δ = 0.004 | pleochroism = Weak; O = pale blue; E = pale pinkish brown | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

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