Bityite
A rare lithium-bearing member of the margarite mica subgroup, first described by Lacroix in 1908.
Intro adapted from Wikipedia (CC BY-SA).
Bityite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaLiAl₂(Si₂BeAl)O₁₀(OH)₂.
It crystallizes in the monoclinic crystal system (space group Cc). It is a member of the Mica, Clay structural group.
Key properties: Mohs hardness 4–4.5; specific gravity 3.02–3.05; Vitreous, pearly on cleavages luster; refractive index 1.657; optically biaxial.
IMA symbol Bty, IMA status: approved, named in 1908.
A late-stage mineral in lithium-bearing pegmatites.
It is found associated with Tourmaline, albite, lepidolite (Mt. Bity, Madagascar); bavenite, beryl, albite, cassiterite, columbite, tourmaline (Londonderry, Australia); calcite.
The name is derived from the locality, Mt. Bity, Madagascar.