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Pyrrhotite

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Formula:
Fe7S8
Also given as Fe1-x (x = 0 to 0.17). The various polytypes known have slightly different stoichiometries.
Colour:
Bronze brown, bronze red, or dark brown
Lustre:
Metallic
Hardness:
3½ - 4
Specific Gravity:
4.58 - 4.65
Crystal System:
Monoclinic
Name:
Named in 1847 by Ours-Pierre-Armand Petit-Dufrénoy from Greek πνρρός "pyrrhos", flame-colored.
Pyrrhotite is found with pentlandite in basic igneous rocks, veins, and metamorphic rocks. It is also often found with pyrite, marcasite, and magnetite. It has varying magnetic powers, depending on the number of Fe vacancies in the crystal structure. A related species with no vacancies (and therefore non-magnetic), is called troilite and has been found in meteorites and rarely terrestrially.

Several polytypes are known; the most common one is pyrrhotite-4M.

Visually similar to smythite and troilite.

Compare 'UM1989-25-S:FeNi' - a representative of the Fe1-xS-Ni1-xS (Mss) solid solution.


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Classification of PyrrhotiteHide

Approved, 'Grandfathered' (first described prior to 1959)
2.CC.10

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
C : Metal Sulfides, M: S = 1: 1 (and similar)
C : With Ni, Fe, Co, PGE, etc.
2.8.10.1

2 : SULFIDES
8 : AmXp, with m:p = 1:1
3.9.1

3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
9 : Sulphides etc. of Fe

Pronounciation of PyrrhotiteHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Physical Properties of PyrrhotiteHide

Metallic
Transparency:
Opaque
Colour:
Bronze brown, bronze red, or dark brown
Comment:
Tarnishes quickly
Streak:
Dark grayish black
Hardness:
3½ - 4 on Mohs scale
Hardness:
VHN100=373 - 409 kg/mm2 - Vickers
Cleavage:
None Observed
Parting:
Distinct on {0001}
Fracture:
Sub-Conchoidal
Density:
4.58 - 4.65 g/cm3 (Measured)    4.69 g/cm3 (Calculated)

Optical Data of PyrrhotiteHide

Type:
Anisotropic
Anisotropism:
Strong
Pleochroism:
Weak

Chemical Properties of PyrrhotiteHide

Formula:
Fe7S8

Also given as Fe1-x (x = 0 to 0.17). The various polytypes known have slightly different stoichiometries.
Common Impurities:
Ni,Co,Cu

Age informationHide

Age range:
Early Cretaceous : 141 ± 9.9 Ma to 141 ± 9.9 Ma - based on data given below.
Sample ages:
Sample IDRecorded ageGeologic TimeDating method
1141 ± 9.9 MaEarly CretaceousRe-Os
Sample references:
IDLocalityReference
1Chaoshan Au deposit, Shizishan ore field, Tongling Prefecture, Anhui Province, ChinaWang, J. Z., Li, J. W., Zhao, X. F., Ma, C. Q., Qu, W. J., & Du, A. D. (2008) Re-Os dating of pyrrhotite from the Chaoshan gold skarn, eastern Yangtze Craton, eastern China. International Geology Review, 50(4), 392-406.

Crystallography of PyrrhotiteHide

Polytype:
Formula:
Crystal System:
Class (H-M)
Space Group:
Space Group Setting:
Cell Parameters:
Ratio:
Unit Cell Volume (calc):
Z:
Pyrrhotite-11CPyrrhotite-11HPyrrhotite-4MPyrrhotite-5CPyrrhotite-6CPyrrhotite-7H
Fe10S11Fe10S11Fe7S8Fe9S10Fe11S12Fe9S10
Orthorhombic Hexagonal Monoclinic Monoclinic Monoclinic Hexagonal 
  2/m - Prismatic2 - Sphenoidalm - Domatic 
  B2/b P21 Bb  
  C2/c P21 Cc  
a = 3.433(9) Å, b = 5.99(2) Å, c = 5.7432(5) Å
β = 90°

a = 11.88 Å, b = 6.87 Å, c = 22.79 Å
β = 90.47°
a = 6.8673(4) Å, b = 28.6536(9) Å, c = 6.8592(4) Å
β = 119.975(7)°
a = 6.8973(15) Å, b = 11.954(3) Å, c = 17.602(4) Å
α = 90°, β = 101.302(4)°, γ = 90°

a:b:c = 0.573 : 1 : 0.959 a:b:c = 1.729 : 1 : 3.317a:b:c = 0.24 : 1 : 0.239a:b:c = 0.577 : 1 : 1.472 
V 118.10 ų
(Calculated from Unit Cell)
 V 1,859.96 ų
(Calculated from Unit Cell)
V 1169.18 ųV 1423.1 ų 
   44 

Crystallographic forms of PyrrhotiteHide

Crystal Atlas:
Image Loading
Click on an icon to view
Pyrrhotite no.15 - Goldschmidt (1913-1926)
Pyrrhotite - {101}, {001}
Pyrrhotite - {100}, {001}
Pyrrhotite - Contact twin on {10-12}
3d models and HTML5 code kindly provided by www.smorf.nl.

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Transparency
Opaque | Translucent | Transparent

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Epitaxial Relationships of PyrrhotiteHide

Epitaxial Minerals:
Epitaxy Comments:
Usually, the pyrrhotite is on the galena, but codepositing intergrowths are known. The "six-fold" axis of pyrrhotite is parallel to the three-fold axis (octahedral axis) in galena.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.00 (4)
2.65 (6)
2.08 (10)
1.728 (5)
1.328 (4)
1.105 (4)
1.052 (3)

Synonyms of PyrrhotiteHide

Other Language Names for PyrrhotiteHide

Basque:Pirrotita
Catalan:Pirrotina
Czech:Pyrhotin
French:Pyrrhotite
Italian:Pirrotite
Japanese:磁硫鉄鉱
Lithuanian:Pirotinas
Norwegian (Bokmål):Magnetkis
Polish:Pirotyn
Portuguese:Pirrotite
Simplified Chinese:磁黄铁矿
Slovak:Pyrotit
Swedish:Magnetkis
Traditional Chinese:磁黃鐵礦
Ukrainian:Піротин

Varieties of PyrrhotiteHide

Cobaltoan PyrrhotiteA cobalt-bearing variety of pyrrhotite.
Nickeloan PyrrhotiteA nickel-bearing variety of pyrrhotite.

Relationship of Pyrrhotite to other SpeciesHide

Other Members of this group:
Smythite(Fe,Ni)3+xS4 (x=0-0.3)Trig. 3m (3 2/m) : R3m
TroiliteFeSHex. 6/mmm (6/m 2/m 2/m) : P63/mmc

Common AssociatesHide

Associated Minerals Based on Photo Data:
Quartz391 photos of Pyrrhotite associated with Quartz on mindat.org.
Calcite307 photos of Pyrrhotite associated with Calcite on mindat.org.
Sphalerite284 photos of Pyrrhotite associated with Sphalerite on mindat.org.
Siderite253 photos of Pyrrhotite associated with Siderite on mindat.org.
Pyrite209 photos of Pyrrhotite associated with Pyrite on mindat.org.
Galena196 photos of Pyrrhotite associated with Galena on mindat.org.
Dolomite119 photos of Pyrrhotite associated with Dolomite on mindat.org.
Chalcopyrite119 photos of Pyrrhotite associated with Chalcopyrite on mindat.org.
Marcasite48 photos of Pyrrhotite associated with Marcasite on mindat.org.
Arsenopyrite48 photos of Pyrrhotite associated with Arsenopyrite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

2.CC.UM2007-26-S:CuFeIrNiPtRh(Ir,Cu,Ni,Pt,Rh,Fe)9S11
2.CC.05Achávalite(Fe,Cu)SeHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
2.CC.05BreithauptiteNiSbHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
2.CC.05FrebolditeCoSeHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
2.CC.05KotulskitePd(Te,Bi)Hex.
2.CC.05Langisite(Co,Ni)AsHex. 6 : P63
2.CC.05NickelineNiAsHex. 6/mmm (6/m 2/m 2/m) : P63/mcm
2.CC.05Sederholmitebeta-NiSeHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
2.CC.05SobolevskitePd(Bi,Te)Hex.
2.CC.05StumpflitePt(Sb,Bi)Hex.
2.CC.05Sudburyite(Pd,Ni)SbHex.
2.CC.05JaipuriteCoSHex.
2.CC.05ZlatogoriteNiCuSb2Trig.
2.CC.10Smythite(Fe,Ni)3+xS4 (x=0-0.3)Trig. 3m (3 2/m) : R3m
2.CC.10TroiliteFeSHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
2.CC.15CherepanoviteRhAsOrth. mmm (2/m 2/m 2/m) : Pnma
2.CC.15Modderite(Co,Fe)AsOrth.
2.CC.15Ruthenarsenite(Ru,Ni)AsOrth.
2.CC.15Westerveldite(Fe,Ni,Co)AsOrth.
2.CC.20MilleriteNiSTrig. 3m : R3m
2.CC.20Mäkineniteγ-NiSeTrig.
2.CC.20UM1990-38-S:CuFeIrNiPtRh(Ni,Fe,Rh,Cu,Ir,Pt)S
2.CC.25Mackinawite(Fe,Ni)9S8Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm
2.CC.30Hexatestibiopanickelite(Pd,Ni)(Sb,Te)Hex.
2.CC.30VavříniteNi2SbTe2Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc
2.CC.35aBraggite(Pt,Pd,Ni)STet.
2.CC.35bCooperitePtSTet. 4/mmm (4/m 2/m 2/m) : P42/mmc
2.CC.35aVysotskite(Pd,Ni)STet.

Related Minerals - Dana Grouping (8th Ed.)Hide

2.8.10.2Smythite(Fe,Ni)3+xS4 (x=0-0.3)Trig. 3m (3 2/m) : R3m

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

3.9.3PyriteFeS2Iso. m3 (2/m 3) : Pa3
3.9.4MarcasiteFeS2Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.5GreigiteFe2+Fe3+2S4Iso. m3m (4/m 3 2/m) : Fd3m
3.9.6Mackinawite(Fe,Ni)9S8Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm
3.9.7Smythite(Fe,Ni)3+xS4 (x=0-0.3)Trig. 3m (3 2/m) : R3m
3.9.8Achávalite(Fe,Cu)SeHex. 6/mmm (6/m 2/m 2/m) : P63/mmc
3.9.9FerroseliteFeSe2Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.10FrohbergiteFeTe2Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.11LöllingiteFeAs2Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.12ArsenopyriteFeAsSMon. 2/m : P21/b
3.9.13GudmunditeFeSbSMon. 2/m : P21/b

Other InformationHide

Notes:
Variably magnetic
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Pyrrhotite in petrologyHide

Common component of (items highlighted in red)

References for PyrrhotiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Palache, C., Berman, H., Frondel, C. (1944) The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged, 834pp.: 231-235.
Kiskyras, D.A. (1950) The magnetic properties of pyrrhotite at various temperatures with special regard to its origin. Neues Jahrbuch für Mineralogie, Geologie und Paläontologie, Abhandlungen, Abteilung A: Mineralogie, Petrographie 80A, 297-342.
Campbell, F.A. (1963) Sphalerite-pyrrhotite relationships at Quemont Mine. The Canadian Mineralogist: 7: 367-374.
Carpenter, R.H., Desborough, G.A. (1964) Range in solid solution and structure of naturally occurring troilite and pyrrhotite. American Mineralogist: 49: 1350-1365.
Arnold, R.G. (1967) Range in composition and structure of 82 natural terrestrial pyrrhotites. The Canadian Mineralogist: 9: 31-50.
Fleet, M.E., MacRae, N. (1969) Two-phase hexagonal pyrrhotites. The Canadian Mineralogist: 9: 699-705.
Graham, A.R. (1969) Quantitative determination of hexagonal and monoclinic pyrrhotites by X-ray diffraction. The Canadian Mineralogist: 10: 4-24.
Clark, A. H. (1970) Quantitative determination of hexagonal and monoclinic pyrrhotites by X-ray diffraction: A discussion. The Canadian Mineralogist: 10: 278-280.
Yund, R.A., Hall, H.T. (1970) Kinetics and mechanism of pyrite exsolution from pyrrhotite. Journal of Petrology: 11: 381-404.
Fleet, M.E. (1971) The crystal structure of a pyrrhotite (Fe7S8). Acta Crystallographica: B27: 1864-1867.
Tokonami, M., Nishiguchi, K., Morimoto, N. (1971) Crystal structure of monoclinic pyrrhotite. American Mineralogist: 57: 1066-1080.
Batt, A.P. (1972) Nickel distribution in hexagonal and monoclinic pyrrhotite. The Canadian Mineralogist: 11: 892-897.
Carpenter, H.R., Bailey, A.C. (1973) Application of Ro and Ar measurements to the study of pyrrhotite and troilite. American Mineralogist: 58: 440-443.
Vaughan, D.J. (1973) Variation in properties of synthetic "pyrrhotites" of composition Fe (sub 1-x) S (O< or =x< or =0.14). The Canadian Mineralogist: 11: 1008-1011.
Ramsden, A.R. (1975) Compositions of coexisting pyrrhotites, pentlandites and pyrites at Spargoville, Western Australia. The Canadian Mineralogist: 13: 133-137.
Morimoto, N., Gyobu, A., Mukaiyama, H., Izawa, E. (1975) Crystallography and stability of pyrrhotites. Economic Geology: 70: 824-833.
Corlett, M. (1977) Iron oxides and pyrrhotites from Igdlukunguaq, Disko Island, Greenland. The Canadian Mineralogist: 15: 540-545.
Fleet, M.E. (1978) The pyrrhotite-marcasite transformation. The Canadian Mineralogist: 16: 31-35.
Kuebler, L. (1981) Note on the hardness of hexagonal pyrrhotite and a method for measuring the abrasion depth in sulfides. The Canadian Mineralogist: 19: 355-359.
King, H.E., Jr., Prewitt, C.T. (1982) High-pressure and high-temperature polymorphism of iron sulfide (FeS). Acta Crystallographica: B38: 1877-1887. [doi:10.1107/S0567740882007523]
Campbell, F.A., Ethier, V.G. (1984) Nickel and cobalt in pyrrhotite and pyrite from the Faro and Sullivan orebodies. The Canadian Mineralogist: 22: 503-506.
Pasquariello, D. M., Kershaw, R., Passaretti, J. D., Dwight, K., Wold, A. (1984) Low-temperature synthesis and properties of Co9S8, Ni3S2, and Fe7S8. Inorganic Chemistry: 23: 872-874.
Keller-Besrest, F., Collin, G. (1990) Structural aspects of the α transition in stoichiometric FeS: identification of the high-temperature phase. Journal of Solid State Chemistry: 84: 194-210.
Barkov, A.Y., Laajoki, K.V.O., Men'shikov, Y.P., Alapieti, T.T., Sivonen, S.J. (1997) First terrestrial occurrence of titanium-rich pyrrhotite, marcasite and pyrite in a fenitized xenolith from the Khibina alkaline complex, Russia. The Canadian Mineralogist: 35: 875-885.
Nesbitt, H.W., Schaufuss, A.G., Scaini, M., Bancroft, G.M., Szargan, R. (2001) XPS measurement of fivefold and sixfold coordinated sulfur in pyrrhotites and evidence for millerite and pyrrhotite surface species. American Mineralogist: 86: 318-326.
Farrell, S.P., Fleet, M.E. (2002) Phase separation in (Fe,Co)1-xS monosulfide solid-solution below 450°C, with consequences for coexisting pyrrhotite and pentlandite in magmatic sulfide deposits. The Canadian Mineralogist: 40: 33-46.
Froese, E. (2003) Point defects in pyrrhotite. The Canadian Mineralogist: 41: 1061-1067.
Selivanov, E.N., Vershinin, A.D., Gulyaeva, R.I. (2003) Thermal expansion of troilite and pyrrhotine [sic] in helium and air. Inorganic Materials: 39: 1097-1102.
Powell, A.V., Vaqueiro, P., Knight, K.S., Chapon, L.C., Sanchez, R.D. (2004) Structure and magnetism in synthetic pyrrhotite Fe7S8: a powder neutron-diffraction study. Phys. Rev., Serie 3.B - Condensed Matter: 70: 014415-1 - 014415-12.
Wang, H., Salveson, I. (2005) A review on the mineral chemistry of the non-stoichiometric iron sulphide, Fe1-xS (0≤x≤0.125): polymorphs, phase relations and transitions, electronic and magnetic structures. Phase Transitions: 78: 547-567.
Makovicky, E. (2006) Crystal structures of sulfides and other chalcogenides. Reviews in Mineralogy and Geochemistry: 61: 7-125.
de Villiers, J.P.R., Liles, D.C. and Becker, M. (2009) The crystal structure of a naturally occurring 5C pyrrhotite from Sudbury, its chemistry, and vacancy distribution. American Mineralogist 94, 1405-1410. [but see Lilies & de Villiers, 2012]
de Villiers, J.P.R., Liles, D.C. (2010) The crystal-structure and vacancy distribution in 6C pyrrhotite. American Mineralogist: 95: 148-152.
Elliot, A.D. (2010): Structure of pyrrhotite 5C (Fe9S10). Acta Crystallographica B66, 271-279.
Becker, M., de Villiers, J., Bradshaw, D. (2010) The Mineralogy and Crystallography of Pyrrhotite from Selected Nickel and PGE Ore Deposits. Economic Geology: 105: 1025-1037.
Harries, D., Pollok, K., Langenhorst, F. (2011) Translation interface modulation in NC-pyrrhotites: Direct imaging by TEM and a model toward understanding partially disordered structural states. American Mineralogist: 96: 716-731.
Lilies, D.C., de Villiers, J.P.R. (2012) Redetermination of the structure of 5C pyrrhotite at low temperature and at room temperature. American Mineralogist: 97: 257-261.

Internet Links for PyrrhotiteHide

Localities for PyrrhotiteHide

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