Girish Mahajan (Editor)

Argentopyrite

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Category
  
Sulfide mineral

Strunz classification
  
2.CB.65

Space group
  
P1121/n

Formula (repeating unit)
  
AgFe2S3

Crystal system
  
Monoclinic

Argentopyrite

Crystal class
  
Prismatic (2/m) (same H-M symbol)

Argentopyrite is a moderately rare sulfide mineral with formula AgFe2S3. It is one of the natural compounds of the M Fe2S3 type, with M being caesium in very rare pautovite, copper in relatively common cubanite, potassium in rare rasvumite and thallium in rare picotpaulite. The type locality is Jáchymov in Czech Republic. Chemically similar mineral include sternbergite (dimorphous with argentopyrite), lenaite, AgFeS2, and argentopentlandite, Ag(Fe,Ni)8S8.

Crystal structure

Although previously assumed orthorhombic, argentopyrite was later shown to be monoclinic, with structural relationship to cubanite. The most important feature of the argentopyrite structure are:

  • hexagonal close-packing of sulfur atoms
  • presence of AgS4 and FeS4 tetrahedra in sheets displaying corner-sharing
  • presence of a cluster of four FeS4 tetrahedra that share edges
  • presence of two iron sites, instead of one as in related species
  • ordered-disordered ferrous-ferric nature of the mineral
  • References

    Argentopyrite Wikipedia