Ammineite

Ammineite is the first recognized mineral containing ammine groups. Its formula is . 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:

Chanabayaite, CuCl·0.25H₂O, a triazolate mineral
Joanneumite, Cu₂₂, an isocyanurate mineral
Shilovite, Cu₄₂

Crystal structure

The characteristic features of the structure of ammineite are:

layers of trans form of the copper complex, parallel to, connected by Cu-Cl bonds
presence of CuN₂Cl₄ distorted octahedron
edge-sharing of the octahedra produce zigzag chains along the 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. Ammonia may be produced in decomposition of compounds like urea or uric acid.