Arakiite Explained

Arakiite
Formula:	(Zn,Mn^2+)(Mn^2+,Mg)12(Fe^3+,Al)2(As^3+O3)(As^5+O4)2(OH)23
Imasymbol:	Ark
Color:	Red-brown to orange-brown
Mohs:	3-4
Luster:	Earthy
Streak:	Pale-brown, red-brown
Diaphaneity:	Translucent, Opaque
Gravity:	3.41
Density:	3.41 g/cm3

Arakiite (IMA symbol: Ark^[1]) is a rare mineral with the formula (Zn,Mn²⁺)(Mn²⁺,Mg)₁₂(Fe³⁺,Al)₂(As³⁺O₃)(As⁵⁺O₄)₂(OH)₂₃.^[2] It is both arsenate and arsenite mineral, a combination that is rare in the world of minerals. Arakiite is stoichiometrically similar to hematolite. It is one of many rare minerals coming from the famous Långban manganese skarn deposit in Sweden. Other minerals bearing both arsenite and zinc include kraisslite and mcgovernite.^[3]

The mineral crystallizes in the monoclinic crystal system in space group Cc.^[4]

Notes and References

1. Warr. L.N.. 2021. IMA-CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
2. Roberts, A.C., Grice, J.D., Cooper, M.A., Hawthorne, F.C., and Feinglos, M.N., 2000. A new Zn-bearing hematolite-like mineral from Långban, Värmland, Sweden. Mineralogical Record 31(3), 253-256
3. Web site: Arakiite: Arakiite mineral information and data . Mindat.org . 2016-03-04.
4. Cooper . M.A. . Hawthorne . F.C. . The Canadian Mineralogist . 37 . 1999 . 1471–1482 . The effect of differences in coordination on ordering of polyvalent cations in close-packed structures: The crystal structure of arakiite and comparison with hematolite.