White pearly crusts of the very rare mineral paraumbite associated to pink eudialyte crystals, from the type locality (Eveslogchorr Mountain, Khibiny Massif, Kola, Russian Federation) and only one of the three known localities worldwide. — Photo: David Hospital · CC BY-SA 4.0
Paraumbite
Paraumbite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₃Zr₂H(Si₃O₉)₂·3H₂O.
It crystallizes in the orthorhombic crystal system.
Key properties: Mohs hardness 4.5; specific gravity 2.59; White streak; Vitreous, pearly on cleavages luster; optically biaxial.
IMA symbol Pumb, IMA status: approved, named in 1982.
Replacing wadeite in a pegmatite in a differentiated alkalic massif (Khibiny massif, Russia); in altered pegmatite and sodalite xenoliths in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).
It is found associated with Eudialyte, wadeite, gaidonnayite, natrolite, pectolite, potassic feldspar (Khibiny massif, Russia); gaidonnayite (Mont Saint-Hilaire, Canada).
Its name comes from the Greek para, for near, and its relation to umbite.