Harman Patil (Editor)

Nabimusaite

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Formula (repeating unit)
  
KCa12(SiO4)4(SO4)2O2F

Space group
  
R3m

Crystal system
  
Trigonal

Category
  
Silicate mineral, nesosilicate

Crystal class
  
Hexagonal scalenohedral (3m) H-M symbol: (3 2m)

Unit cell
  
a = 7.19, b = 7.19 c = 41.25 [Å] (approximated); Z = 3

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

Contents

Associations

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

Crystal structure

Crystal structure of nabimusaite is modular. It is of antiperovskite type. It is composed of:

  • hatrurite-like modules [Ca12(SiO4)4O2F]3+, in the number of three; anions are in octahedral and cations in tetrahedral coordination
  • [K(SO4)2]3 module

    • The two modules are mutually intercalated.

    Origin

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

    References

    Nabimusaite Wikipedia
    (Text) CC BY-SA