Anandite
A rare black phyllosilicate of barium, iron and magnesium with a glassy luster and near-perfect cleavage.
Intro adapted from Wikipedia (CC BY-SA).
Anandite is an IMA-recognized mineral species in the silicate class, with the chemical formula BaFe²⁺₃(Si₃Fe³⁺)O₁₀S(OH).
It crystallizes in the monoclinic crystal system (space group Am). It is a member of the Mica, Clay structural group.
Key properties: Mohs hardness 3–4; specific gravity 3.94; Vitreous luster; refractive index 1.868; optically biaxial.
IMA symbol Ana, IMA status: approved, named in 1966.
Occurs as monomineralic veinlets and lenses in a banded magnetite deposit capped by banded magnetite-barite rock. The ore zone and associated interbedded calc-schists and gneisses are of metasedimentary origin.
It is found associated with Magnetite, chalcopyrite, pyrite, pyrrhotite, barite.
The mineral was named to honor Dr. Ananda Kentush Coomaraswamy (1877–1947), the first Director of the Mineral Survey of Ceylon (Sri Lanka).