Argentopyrite

Argentopyrite
Argentopyrite
	Argentopyrite (from Schneeberg, Erzgebirge, Saxony, Germany)
General
Category	Sulfide mineral
Formula; (repeating unit)	AgFe2S3
IMA symbol	Agpy
Strunz classification	2.CB.65
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) ; (same H-M symbol)
Space group	P1121/n
Identification
Color	Bronze-brown or gray-white; iridescent (many colors)
Crystal habit	Tabular prisms, pseudohexagonal or pseudo-orthorhombic, possibly pyramidally-terminated
Fracture	Uneven
Tenacity	Brittle
Mohs scale hardness	3.5-4
Luster	Metallic
Streak	Grey
Diaphaneity	Opaque
Density	4.25-4.27
References

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 , copper in relatively common cubanite, potassium in rare and thallium in rare . The type locality is Jáchymov in Czech Republic. Chemically similar mineral include (dimorphous with argentopyrite), , AgFeS₂, and , Ag(Fe,Ni)₈S₈.^[2]

Crystal structure[]

Although previously assumed orthorhombic,^[5] argentopyrite was later shown to be monoclinic, with structural relationship to cubanite. The most important feature of the argentopyrite structure are:^[6]

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[]

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ ^a ^b "Argentopyrite - Argentopyrite: Argentopyrite mineral information and data". Retrieved 2016-03-07.
^ "Argentopyrite" (PDF). Retrieved 2016-03-07.
^ Mineralienatlas
^ Murdoch, J., and Berry, L.G., 1954. X-ray measurements on argentopyrite. American Mineralogist 39, 475-485
^ Yang, H., Pinch, W.W., and Downs, R.T., Crystal structure of argentopyrite, AgFe₂S₃, and its relationship with cubanite. American Mineralogist 94, 1727-1730

[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[Mindat-2] "Argentopyrite - Argentopyrite: Argentopyrite mineral information and data". Retrieved 2016-03-07.

[Handbook_of_Mineralogy-3] "Argentopyrite" (PDF). Retrieved 2016-03-07.

[atlas-4] Mineralienatlas

[5] Murdoch, J., and Berry, L.G., 1954. X-ray measurements on argentopyrite. American Mineralogist 39, 475-485

[6] Yang, H., Pinch, W.W., and Downs, R.T., Crystal structure of argentopyrite, AgFe₂S₃, and its relationship with cubanite. American Mineralogist 94, 1727-1730

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