Colorless and very pale blue crystal aggregates of the rare silicate hydroxycancrinite from Lovozero. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Hydroxycancrinite
Hydroxycancrinite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Na,Ca,K)₈(Al₆Si₆O₂₄)(OH,CO₃)₂·2H₂O.
It crystallizes in the hexagonal crystal system (space group P3). It is a member of the Cancrinite, Cancrinite-sodalite structural group.
Key properties: Mohs hardness 6; specific gravity 2.32; White streak; Vitreous luster; optically uniaxial.
IMA symbol Hccn, IMA status: approved, named in 1990.
Found in veins in ultra-agpaitic pegmatites in a differentiated alkalic massif.
It is found associated with Natrolite, steenstrupine, vuonnemite, epistolite, mountainite, ilmajokite, nastrophite.
The name refers to predominant hydroxyl in its composition, and its relation to cancrinite.