Very pale pink crystals of the rare silicate mineral cancrisilite from the type locality in Mt.Alluaiv (Alluaiv Mountains, Lovozero, Kola, Russian Federation) and one of the only 5 mineral localities known worldwide. Part of the holotype specimen used by the author to describe this mineral species, as described in the label. Ex.Dr.Hartel collection. — Photo: David Hospital · CC BY-SA 4.0
Cancrisilite
Cancrisilite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₇(Si₇Al₅)O₂₄(CO₃)·3H₂O.
It crystallizes in the hexagonal crystal system (space group P6_3mc). It is a member of the Cancrinite, Cancrinite-sodalite structural group.
Key properties: Mohs hardness 5; specific gravity 2.4; White streak; Vitreous luster; optically uniaxial.
IMA symbol Cnc, IMA status: approved, named in 1990.
Found in ultra-agpaitic pegmatites in a differentiated alkalic massif.
It is found associated with Potassic feldspar, nepheline, sodalite, arfvedsonite, aegirine, manaksite, eudialyte, lamprophyllite, additional minor minerals.
The name refers to the relatively high ratio of silicon to aluminum, and its relation to cancrinite.