Leucosphenite from the famous Lovozero region in Russia. — Photo: David Hospital · CC BY-SA 4.0
Leucosphenite
Leucosphenite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₄BaTi₂B₂Si₁₀O₃₀.
It crystallizes in the monoclinic crystal system (space group C2/m).
Key properties: Mohs hardness 6–6.5; specific gravity 3.04–3.09; White streak; Vitreous to pearly luster; optically biaxial.
IMA symbol Lsp, grandfathered status — known before the IMA’s founding, named in 1901.
Found in pegmatite in syenite (Greenland, Russia, Canada); in aegirine-feldspar veins (Inagli massif, Russia); an authigenic mineral in shales (Utah and Wyoming, USA).
It is found associated with Elpidite, aegirine, epididymite, albite, polylithionite (Narss^a rssuk, Greenland); arfvedsonite, eudialyte, neptunite, lamprophyllite.
Its name comes from the Greek for white and wedge, its color and crystal habit.