Eveslogite
A highly complex titanium-niobium inosilicate found on Mount Eveslogchorr in Russia's Khibiny Mountains.
Intro adapted from Wikipedia (CC BY-SA).
Eveslogite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Ca,K,Na,Sr,Ba)₄₈(Ti,Nb,Fe,Mn)₁₂(OH)₁₂Si₄₈O₁₄₄(OH,F,Cl)₁₄.
It crystallizes in the monoclinic crystal system (space group P2/m).
Key properties: Mohs hardness 5; specific gravity 2.85; White streak; Vitreous to silky luster; optically biaxial.
IMA symbol Evl, IMA status: approved, named in 2001.
Found in a veinlet that cuts nepheline syenite in an alkaline massif.
It is found associated with Nepheline, K-feldspar, biotite, fluorapatite, shcherbakovite, eudialyte, astrophyllite.
Alludes to the locality, Mt. Eveslogchorr.