Eliseevite
Eliseevite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₁.₅Li{Ti₂O₂[Si₄O₁₀.₅(OH)₁.₅]}·2H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 5; specific gravity 2.68; White streak; Vitreous luster.
IMA symbol Esv, IMA status: approved, named in 2010.
A late-stage, hydrothermal mineral produced through alteration of murmanite, in altered ussingite pegmatites within a layered complex of malignites, foyaites.
It is found associated with Albite, analcime, catapleiite, chabazite-Ca, gmelinite-K, manganoneptunite, microcline, murmanite, ussingite (Mt. Alluaiv); chabazite-Ca, chkalovite.
The mineral was named to honor Nikolai Aleksandrovich Eliseev (1897-1966), Russian geologist and petrologist, Professor at Leningrad State University.