Anandite

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Anandite
General
Category Mica group, phyllosilicate
Formula
(repeating unit)		(Ba,K)(Fe2+,Mg)3(Si,Al,Fe)4O10(S,OH)2
IMA symbol Ana [1]
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
ColorBlack
Crystal habit Massive, prismatic crystals poorly formed produce hexagonal outline cleavage fragments
Cleavage Perfect on {001}
Fracture Flexible fragments
Mohs scale hardness3 – 4
Luster Vitreous
Streak Grey white
Diaphaneity Nearly opaque
Specific gravity 3.94
Optical propertiesBiaxial (+)
Refractive index nα = 1.855 nγ = 1.880
Pleochroism Y = green; Z = brown
References [2] [3] [4]

Anandite is a rare phyllosilicate with formula (Ba,K)(Fe2+,Mg)3(Si,Al,Fe)4O10(S,OH)2. It crystallizes in the monoclinic crystal system. It is black in color with a glassy luster and a near perfect cleavage. [3]

It was first described in 1967 [3] for an occurrence in the Wilagedera Prospect of the North Western Province of Sri Lanka in bands of iron ore. [2] [4] 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. [2] It was named for Ananda Kentish Coomaraswamy (1877–1947), who was the first director of the Mineral Survey of Ceylon, Sri Lanka. [4]

Anandite is a member of the mica group of minerals. [3] Other minerals that anandite is associated with include: magnetite, chalcopyrite, pyrite, pyrrhotite and baryte. [3]

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 3 "Anandite mineral information and data". Mindat.org.
  3. 1 2 3 4 5 "PDF data sheet for Anandite in the Handbook of Mineralogy" (PDF). Handbook of Mineralogy. Mineral Data Publishing. 2001. Retrieved 2008-05-04.
  4. 1 2 3 "Anandite mineral data sheet". Webmineral.com. Archived from the original on 6 May 2008. Retrieved 2008-05-04.


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