White crytals of the extremely rare mineral cryptophyllite from the TL and only known locality worldwide in Russia (Tsentral'nyi Mine, Rasvumchorr Mountain, Khibiny Massif, Murmansk Oblast, Russian Federation). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Cryptophyllite
Cryptophyllite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₂Ca[Si₄O₁₀]·5H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/n).
Key properties: specific gravity 2.185; White streak; Vitreous luster; optically biaxial.
IMA symbol Cp, IMA status: approved, named in 2008.
A late-stage hydrothermal mineral along fractures in a high-potassium peralkaline pegmatite in urtite rocks near the contact with nepheline-apatite rock.
It is found associated with Shlykovite.
Derived from the Greek words “κρυπτοζ”- concealed (crypto) and “φυλλον” - leaf as an allusion to its occurrence in intimate intergrowths with visually indistinguishable shlykovite and to its layered s.