Ammineite

Ammineite
General
Category Chloride mineral
Formula
(repeating unit)		 CuCl2(NH3)2
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Cmcm
Unit cell a = 7.79, b = 10.64
c = 5.84 [Å] (approximated)
Identification
Color Blue
Crystal habit Hypidiomorphic crystals; powdery masses
Mohs scale hardness 1
Luster Vitreous
Streak Light blue
Density 2.38 (calculated)
Pleochroism Dark blue to light blue
References [1][2]

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.[1][2] At the same site other ammine-containing minerals were later found:[3] [4][5][6]

Crystal structure

The characteristic features of the structure of ammineite are:[1]

  • 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.[1]

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. Ammonia may be produced in decomposition of compounds like urea or uric adic.[1]

References

  1. 1 2 3 4 5 Bojar, H.P, Walter, F., Baumgartner, J., and Färber, G. 2010. Ammineite, CuCl2(NH3)2, a new species containing an ammine complex: mineral data and crystal structure. The Canadian Mineralogist 48(6), 1359-1371.
  2. 1 2 Mindat, Ammineite, http://www.mindat.org/min-38895.html
  3. ↑ Mindat, Pabellón de Pica, http://www.mindat.org/loc-192704.html
  4. ↑ Mindat, Chanabayaite, http://www.mindat.org/min-43945.html
  5. ↑ Mindat, Joanneumite, http://www.mindat.org/min-42755.html
  6. ↑ Mindat, Shilovite, http://www.mindat.org/min-46139.html
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.