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-4C.

Visually similar to smythite and troilite.

Compare 'UM1989-25-S:FeNi' - a representative of the Fe_1-xS-Ni_1-xS (Mss) solid solution.

Classification of PyrrhotiteHide

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IMA status:

Approved, 'Grandfathered' (first described prior to 1959)

Strunz 8th ed.:

2/C.19-20

Nickel-Strunz 10th (pending) ed.:

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.

Dana 8th ed.:

2.8.10.1

2 : SULFIDES
8 : A_mX_p, with m:p = 1:1

Hey's CIM Ref.:

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

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Pronounciation:

Play	Recorded by	Country
	Jolyon & Katya Ralph	United Kingdom

Physical Properties of PyrrhotiteHide

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Lustre:

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

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Type:

Anisotropic

Anisotropism:

Strong

Pleochroism:

Weak

Chemical Properties of PyrrhotiteHide

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Formula:

Fe₇S₈

Also given as Fe_1-x (x = 0 to 0.17). The various polytypes known have slightly different stoichiometries.

Elements listed:

Fe, S - search for minerals with similar chemistry

Common Impurities:

Ni,Co,Cu

Crystallography of PyrrhotiteHide

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Polytype:

Formula:

Crystal System:

Class (H-M)

Space Group:

Space Group Setting:

Cell Parameters:

Ratio:

Unit Cell Volume (calc):

Pyrrhotite-11C	Pyrrhotite-11H	Pyrrhotite-4C	Pyrrhotite-5C	Pyrrhotite-6C	Pyrrhotite-7H
Fe₁₀S₁₁	Fe₁₀S₁₁	Fe₇S₈	Fe₉S₁₀	Fe₁₁S₁₂	Fe₉S₁₀
Orthorhombic	Hexagonal	Monoclinic	Monoclinic	Monoclinic	Hexagonal
		2/m - Prismatic	2 - Sphenoidal	m - 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 : 3.317	a:b:c = 0.24 : 1 : 0.239	a:b:c = 0.577 : 1 : 1.472
V 118.10 Å³ (Calculated from Unit Cell)		V 1,859.96 Å³ (Calculated from Unit Cell)	V 1169.18 Å³	V 1423.1 Å³
			4	4

Crystallographic forms of PyrrhotiteHide

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Crystal Atlas:

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Pyrrhotite no.15 - Goldschmidt (1913-1926)

Pyrrhotite - {101}, {001}

Pyrrhotite - {100}, {001}

Pyrrhotite - Contact twin on {10-12}

Epitaxial Relationships of PyrrhotiteHide

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Epitaxial Minerals:

Galena

PbS

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

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Powder Diffraction Data:

d-spacing	Intensity
3.00	(4)
2.65	(6)
2.08	(10)
1.728	(5)
1.328	(4)
1.105	(4)
1.052	(3)

Synonyms of PyrrhotiteHide

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Dipyrite (of Readwin)

Kroeberite

Magnetic Iron Pyrites

Other Language Names for PyrrhotiteHide

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Basque:Pirrotita

Catalan:Pirrotina

Czech:Pyrhotin

Dutch:Pyrrhotiet

Finnish:Magneettikiisu

French:Pyrrhotite

German:Pyrrhotin
Magnetkies
Magnetopyrit
Pyrrhotit
Pyrrohotit

Hebrew:פירוטיט

Italian:Pirrotite

Japanese:磁硫鉄鉱

Lithuanian:Pirotinas

Norwegian:Magnetkis

Polish:Pirotyn

Portuguese:Pirrotite

Russian:Пирротин

Simplified Chinese:磁黄铁矿

Slovak:Pyrotit

Spanish:Pirrotita
Magnetopirita
Pirita Magnética

Swedish:Magnetkis

Traditional Chinese:磁黃鐵礦

Ukrainian:Піротин

Varieties of PyrrhotiteHide

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Cobaltoan Pyrrhotite	A cobalt-bearing variety of pyrrhotite.
Nickeloan Pyrrhotite	A nickel-bearing variety of pyrrhotite. Note, however, that there are several iron-nickel sulphides.

Relationship of Pyrrhotite to other SpeciesHide

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Member of:

Pyrrhotite Group

Other Members of this group:

Smythite	(Fe,Ni)_3+xS₄ (x=0-0.3)	Trig. 3m (3 2/m) : R3m
Troilite	FeS	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc

Common AssociatesHide

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Associated Minerals Based on Photo Data:

Quartz	391 photos of Pyrrhotite associated with Quartz on mindat.org.
Calcite	307 photos of Pyrrhotite associated with Calcite on mindat.org.
Sphalerite	284 photos of Pyrrhotite associated with Sphalerite on mindat.org.
Siderite	253 photos of Pyrrhotite associated with Siderite on mindat.org.
Pyrite	209 photos of Pyrrhotite associated with Pyrite on mindat.org.
Galena	196 photos of Pyrrhotite associated with Galena on mindat.org.
Dolomite	119 photos of Pyrrhotite associated with Dolomite on mindat.org.
Chalcopyrite	119 photos of Pyrrhotite associated with Chalcopyrite on mindat.org.
Marcasite	48 photos of Pyrrhotite associated with Marcasite on mindat.org.
Arsenopyrite	48 photos of Pyrrhotite associated with Arsenopyrite on mindat.org.

Related Minerals - Nickel-Strunz Grouping Hide

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2.CC.	UM2007-26-S:CuFeIrNiPtRh	(Ir,Cu,Ni,Pt,Rh,Fe)₉S₁₁
2.CC.05	Achávalite	(Fe,Cu)Se	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
2.CC.05	Breithauptite	NiSb	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
2.CC.05	Freboldite	CoSe	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
2.CC.05	Kotulskite	Pd(Te,Bi)	Hex.
2.CC.05	Langisite	(Co,Ni)As	Hex. 6 : P6₃
2.CC.05	Nickeline	NiAs	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mcm
2.CC.05	Sederholmite	beta-NiSe	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
2.CC.05	Sobolevskite	Pd(Bi,Te)	Hex.
2.CC.05	Stumpflite	Pt(Sb,Bi)	Hex.
2.CC.05	Sudburyite	(Pd,Ni)Sb	Hex.
2.CC.05	Jaipurite	CoS	Hex.
2.CC.05	Zlatogorite	NiCuSb₂	Trig.
2.CC.10	Smythite	(Fe,Ni)_3+xS₄ (x=0-0.3)	Trig. 3m (3 2/m) : R3m
2.CC.10	Troilite	FeS	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
2.CC.15	Cherepanovite	RhAs	Orth. mmm (2/m 2/m 2/m) : Pnma
2.CC.15	Modderite	(Co,Fe)As	Orth.
2.CC.15	Ruthenarsenite	(Ru,Ni)As	Orth.
2.CC.15	Westerveldite	(Fe,Ni,Co)As	Orth.
2.CC.20	Millerite	NiS	Trig. 3m : R3m
2.CC.20	Mäkinenite	γ-NiSe	Trig.
2.CC.20	UM1990-38-S:CuFeIrNiPtRh	(Ni,Fe,Rh,Cu,Ir,Pt)S
2.CC.25	Mackinawite	(Fe,Ni)₉S₈	Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm
2.CC.30	Hexatestibiopanickelite	(Pd,Ni)(Sb,Te)	Hex.
2.CC.30	Vavřínite	Ni₂SbTe₂	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
2.CC.35a	Braggite	(Pt,Pd,Ni)S	Tet.
2.CC.35b	Cooperite	PtS	Tet. 4/mmm (4/m 2/m 2/m) : P4₂/mmc
2.CC.35a	Vysotskite	(Pd,Ni)S	Tet.

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

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2.8.10.2

Smythite

(Fe,Ni)_3+xS₄ (x=0-0.3)

Trig. 3m (3 2/m) : R3m

Related Minerals - Hey's Chemical Index of Minerals Grouping Hide

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3.9.3	Pyrite	FeS₂	Iso. m3 (2/m 3) : Pa3
3.9.4	Marcasite	FeS₂	Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.5	Greigite	Fe²⁺Fe³⁺₂S₄	Iso. m3m (4/m 3 2/m) : Fd3m
3.9.6	Mackinawite	(Fe,Ni)₉S₈	Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm
3.9.7	Smythite	(Fe,Ni)_3+xS₄ (x=0-0.3)	Trig. 3m (3 2/m) : R3m
3.9.8	Achávalite	(Fe,Cu)Se	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
3.9.9	Ferroselite	FeSe₂	Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.10	Frohbergite	FeTe₂	Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.11	Löllingite	FeAs₂	Orth. mmm (2/m 2/m 2/m) : Pnnm
3.9.12	Arsenopyrite	FeAsS	Mon. 2/m : P2₁/b
3.9.13	Gudmundite	FeSbS	Mon. 2/m : P2₁/b

Other InformationHide

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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

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An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.

Ore
- Iron ore
  - ⓘ Iron sulfide ore

References for PyrrhotiteHide

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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 a monoclinic pyrrhotite (Fe7S8). 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 Liles & 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.

Liles, 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.

Ssu Han Li, Yen-Hua Chen, Jey-Jau Lee, Hwo-Shuenn Sheu (2018): Phase transition of iron sulphide minerals under hydrothermal conditions and magnetic investigations. Physics and Chemistry of Minerals 45, 27-38.