Chemistry:Nabimusaite

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Nabimusaite
General
CategorySilicate mineral, nesosilicate
Formula
(repeating unit)
KCa12(SiO4)4(SO4)2O2F
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2m)
Space groupR3m
Unit cella = 7.19, b = 7.19
c = 41.25 [Å] (approximated); Z = 3
Identification
ColorColorless
Cleavage(001), imperfect
TenacityBrittle
Mohs scale hardness5
|re|er}}Vitreous
StreakWhite
Density3.12 (calculated) (approximated)
Optical propertiesUniaxial (-)
Refractive indexnω=1.64, nε=1.64 (approximated)
References[1][2]

Nabimusaite is a very rare mineral with formula KCa12(SiO4)4(SO4)2O2F.[1] Its structure, as in case of similar aradite and zadovite, is a derivative of the one of hatrurite.[3] Nabimusaite gives its name to the nabimusaite group.[4] The mineral was found in a pyrometamorphic rock of the Hatrurim Formation, a site known for the natural pyrometamorphism. It is interpreted to have formed due to interaction of a precursor assemblage with sulfate-rich melt.[1] Nabimusaite is potassium- and fluorine-analogue of dargaite.[5]

Associations

Nabimusaite was discovered in nodules composed of larnite and ye'elimite, in a rock formed due to pyrometamorphism.[1]

Notes on chemistry

Nabimusaite is impure as it has a phosphorus admixture.[1]

Crystal structure

Crystal structure of nabimusaite is modular. It is of antiperovskite type. It is composed of hatrurite-like modules [Ca12(SiO4)4O2F]3+ anions in octahedral and cations in tetrahedral coordination with [K(SO4)2]3 modules. The two modules are mutually intercalated.[1]

Origin

Nabimusaite is suggested to result from interaction of a melt, rich in potassium and sulfate, with earlier minerals (ellestadite and larnite).[1]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Galuskin, E.V., Gfeller, F., Armbruster, T., Galuskina, I.O., Vapnik, Y., Murashko, M., Włodyka, R., and Dzierżanowski, P., 2015. New minerals with a modular structure derived from hatrurite from the pyrometamorphic Hatrurim Complex. Part I. Nabimusaite, KCa12(SiO4)4(SO4)2O2F, from larnite rocks of Jabel Harmun, Palestinian Autonomy, Israel. Mineralogical Magazine 79(5), 1061-1072
  2. "Nabimusaite: Nabimusaite mineral information and data". http://www.mindat.org/min-43580.html. Retrieved 2016-03-02. 
  3. Galuskin, E.V., Gfeller, F., Galuskina, I.O., Pakhomova, A., Armbruster, T., Vapnik, Y., Włodyka, R., Dzierżanowski, P., and Murashko, M., 2015. New minerals with a modular structure derived from hatrurite from the pyrometamorphic Hatrurim Complex. Part II. Zadovite, BaCa6[(SiO4)(PO4)](PO4)2F and aradite, BaCa6[(SiO4)(VO4)](VO4)2F, from paralavas of the Hatrurim Basin, Negev Desert, Israel. Mineralogical Magazine 79(5), 1073-1087
  4. "Nabimusaite: Nabimusaite mineral information and data". http://www.mindat.org/min-43580.html. Retrieved 2016-03-02. 
  5. "Nabimusaite: Nabimusaite mineral information and data". http://www.mindat.org/min-43580.html. Retrieved 2016-03-02.