Puneet Varma (Editor)

Ammineite

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Category
  
Chloride mineral

Crystal system
  
Orthorhombic

Formula (repeating unit)
  
CuCl2(NH3)2

Space group
  
Cmcm

Crystal class
  
Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)

Unit cell
  
a = 7.79, b = 10.64 c = 5.84 [Å] (approximated)

Ammineite is the first recognized mineral containing ammine groups. Its formula is [CuCl2(NH3)2]. The mineral is chemically pure. It was found in a guano deposit in Chile. At the same site other ammine-containing minerals were later found:

Contents

  • Chanabayaite, CuCl(N3C2H2)(NH3)·0.25H2O (an alternative formula), a triazolate mineral
  • Joanneumite, Cu(C3N3O3H2)2(NH3)2, an isocyanurate mineral
  • Shilovite, Cu(NH3)4(NO3)2

    • Crystal structure

    The characteristic features of the structure of ammineite are:

  • layers of trans form of the copper complex, parallel to (001), connected by Cu-Cl bonds
  • presence of CuN2Cl4 distorted octahedron ([4+2] coordination)
  • edge-sharing of the octahedra produce zigzag chains along the [001] direction
  • hydrogen bonds between NH3 and Cl atoms

    • Associated minerals

    Ammineite coexists with atacamite, darapskite, halite and salammoniac.

    Origin

    Ammineite is supposed to be a result of an interaction of an earlier copper mineral, likely from a plutonic rock, with ammonia in guano. Ammoniamay be produced in decomposition of compounds like urea or uric adic.

    References

    Ammineite Wikipedia
    (Text) CC BY-SA