Argentopyrite
From Infogalactic: the planetary knowledge core
| Argentopyrite | |
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Argentopyrite (from Schneeberg, Erzgebirge, Saxony, Germany)
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| General | |
| Category | Sulfide mineral |
| Formula (repeating unit) |
AgFe2S3 |
| Strunz classification | 2.CB.65 |
| Crystal symmetry | Monoclinic 2/m |
| Identification | |
| Color | Bronze-brown or gray-white; iridescent (many colors) |
| Crystal habit | Tabular prisms, pseudohexagonal, possibly pyramidally-terminated |
| Crystal system | Monoclinic - prismatic (pseudo-orthorhombic) |
| Fracture | Uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 3.5-4 |
| Luster | Metallic |
| Streak | Grey |
| Diaphaneity | Opaque |
| Density | 4.25-4.27 |
| References | [1][2] |
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.[1]
Crystal structure
Although previously assumed orthorhombic,[3] argentopyrite was later shown to be monoclinic, with structural relationship to cubanite. The most important feature of the argentopyrite structure are:[4]
- 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
- ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 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
