Carletonite is a rare silicate mineral with formula KNa4Ca4(CO3)4Si8O18(F,OH)·(H2O).
It is a phyllosilicate and a member of the apophyllite 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 It was first described in 1969 for an occurrence at Mont Saint-Hilaire. The type locality at Mont Saint–Hilaire is the only reported occurrence.
It occurs in hornfels xenoliths intrusion. It occurs in association with quartz , narsarsukite, ancylite, lorenzenite , pectolite, microcline