Pearly white to pinkish plates over 1.5cm of the extremely rare mineral fivegite from the TL (Tsentral'nyi Mine, Rasvumchorr Mountain, Khibiny Massif, Murmansk Oblast, Russian Federation) and only known locality worldwide. Ex-Dr. Igor Pekov's study material with which he described the species. Analyzed by EDS/XRD. Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Fivegite
Fivegite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₄Ca₂[AlSi₇O₁₇(O₂₋ₓ(OH)ₓ)][(H₂O)₂₋ₓ(OH)ₓ]Cl (x = 0-2).
It crystallizes in the orthorhombic crystal system (space group Pm2_1n).
Key properties: Mohs hardness 4; specific gravity 2.42; White streak; Vitreous to pearly luster; optically biaxial.
IMA symbol Fiv, IMA status: approved, named in 2009.
A late-stage hydrothermal phase in high-potassium peralkaline pegmatite in urtite near the contact with nepheline-apatite rock.
It is found associated with Delhayelite, hydrodelhayelite, pectolite, kalborsite.
The mineral was named to honor Russian geologist and mining engineer, Mikhail Pavlovich Fiveg (1899-1986), the pioneer prospector of the Khibiny apatite deposits.