A 7.0 by 5.2 cms polished slab with a 4-sided monograin of grey Nepheline just to the left of center surrounded by white Perlialite, with minor black Aegirine, red-brown Yuksporite, and porcelaineous Microcline. JSS specimen and photo- — Photo: John Sobolewski · CC BY 3.0
Perlialite
Perlialite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₉NaCa(Si₂₄Al₁₂)O₇₂·15H₂O.
It crystallizes in the hexagonal crystal system (space group P6/mmm).
Key properties: Mohs hardness 4–5; specific gravity 2.14; Pearly luster; optically uniaxial.
IMA symbol Pll, IMA status: approved, named in 1982.
Found in nepheline-microcline and sodalite-astrophyllite veins in nepheline-feldspar and sodalite-microcline pegmatites in a differentiated alkalic massif (Khibiny massif, Russia).
It is found associated with Pectolite, kalsilite, aegirine, wadeite, yuksporite (Khibiny massif, Russia).
The name refers to LIliya ALekseevna PERekrest (1928{), Instructor in Mineralogy, Kirov Mining School, Kirovsk, Russia.