Acicular white crystals of the extremely rare mineral paravinogradovite from the type and only known locality worldwide for the mineral in Kukisvumchorr (Kukisvumchorr Mountains, Khibiny Massif, Murmansk Oblast, Russian Federation). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Paravinogradovite
Paravinogradovite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Na, )₂(Ti⁴⁺,Fe³⁺)₄(Si₂O₆)₂(Si₃AlO₁₀)(OH)₄·H₂O.
It crystallizes in the triclinic crystal system (space group P1).
Key properties: Mohs hardness 5; specific gravity 2.77; White streak; Vitreous to pearly luster; optically biaxial.
IMA symbol Pvgd, IMA status: approved, named in 2002.
On albite in miarolitic cavities within a pegmatite at the contact between a xenolith of corundum-bearing hornfels and enclosing foyaite in an alkaline massif. A secondary mineral formed from vinogradovite.
It is found associated with Nepheline, K-feldspar, albite, analcime, natrolite, aegirine, biotite, chlorite, zircon, ilmenite, pyrochlore, ancylite-(Ce), nordstrandite.
The prefix para (Greek for ‘close by’) alludes to the close relationships of the crystal structure and chemical composition to those of vinogradovite.