Punkaruaivite
Punkaruaivite is an IMA-recognized mineral species in the silicate class, with the chemical formula Li{Ti₂(OH)₂[Si₄O₁₁(OH)]}·H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 4.5; specific gravity 2.6; White streak; Vitreous luster; optically biaxial.
IMA symbol Pka, IMA status: approved, named in 2008.
A hydrothermal vein mineral in a ussingite-aegirine-microcline bearing pegmatite in nepheline syenite (Mt. Punkaruaiv); in natrolite-microcline foyalite (Mt. Eveslogschorr).
It is found associated with Belovite-(Ce), chlakovite, ferronordite-(Ce), gmelenite-Ca, manganoneptunite, manganonordite-(Ce), sphalerite, ussingite (Mt. Punkaruaiv); belovite-(La).
The name refers to Mt. Punkaruaiv, Kola Peninsula, Russia, one of the first described localities.