Chemistry:Anandite

Anandite
General
Category	Phyllosilicates
Formula (repeating unit)	(Ba,K)(Fe2+ ,Mg) 3(Si,Al,Fe) 4O 10(S,OH) 2
Strunz classification	9.EC.35
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/m
Unit cell	a = 5.412(5), b = 9.434(5) c = 19.953(10) [Å]; β = 95°; Z = 2
Identification
Color	Black
Crystal habit	Massive, prismatic crystals poorly formed produce hexagonal outline cleavage fragments
Cleavage	Perfect on {001}
Fracture	Flexible fragments
Mohs scale hardness	3 – 4
|re|er}}	Vitreous
Streak	Grey white
Diaphaneity	Nearly opaque
Specific gravity	3.94
Optical properties	Biaxial (+)
Refractive index	nα = 1.855 nγ = 1.880
Pleochroism	Y = green; Z = brown
References

Anandite is a rare phyllosilicate with formula (Ba,K)(Fe2+
,Mg)
3(Si,Al,Fe)
4O
10(S,OH)
2. It crystallizes in the monoclinic crystal system. It is black in color with a glassy luster and a near perfect cleavage.

It was first described in 1967 for an occurrence in the Wilagedera Prospect of the North Western Province of Sri Lanka in bands of iron ore. It has also been found in Big Creek in Fresno County and in Trumball Peak in Mariposa County, California as well as the Sterling Mine in New Jersey. It was named for Ananda Kentish Coomaraswamy (1877–1947), who was the director of the Mineral Survey of Ceylon, Sri Lanka at that time.

Anandite is a member of the mica group of minerals. Other minerals that anandite is associated with include: magnetite, chalcopyrite, pyrite, pyrrhotite and baryte.