Pyrrhotite Mineral Data

Pyrrhotite Mineral Data +

General Pyrrhotite Information

Chemical Formula:

Fe(1-x)S (x=0-0.17)

Composition:

Molecular Weight = 85.12 gm

Iron 62.33 % Fe

Sulfur 37.67 % S

______

100.00 %

Empirical Formula:

Fe²⁺_0.95S

Environment:

Wide spread occurrences in igneous and metamorphic rocks.

IMA Status:

Valid Species (Pre-IMA) 1835

Locality:

Sudbury, Ontario, Canada and Santa Eulalia, Chihuahua, Mexico. Link to MinDat.org Location Data.

Name Origin:

From the Greek, phrrhotes, "redness," in allusion to color.

Synonym:

Magnetic pyrites

Pyrrhotite Image

Images:

Pyrrhotite

Comments: Lustrous sharp crystals of pyrrhotite to 3.5 cm in size with minor sphalerite and chalcopyrite.
Location: Nikolaevskiy mine, Dal'negors, Primorskiy Kray, Russia. Scale: 4 x 5 x 5.5 cm.
© Dan Weinrich

Pyrrhotite Crystallography

Axial Ratios:

a:b:c =1.8647:1:1.7299

Cell Dimensions:

a = 12.811, b = 6.87, c = 11.885, Z = 26; beta = 117.3° V = 929.51 Den(Calc)= 3.95

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: A2/a

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.057(1), 2.635(0.9), 2.966(0.9),

Forms:

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Forms: [ 1 1 0] [ 1 1 2] [ 1 0 2] [ 1 0 0] [ 0 0 1]

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Crystal Structure:

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Tokonami M , Nishiguchi K , Morimoto N , American Mineralogist , 57 (1972) p.1066-1080, Crystal structure of a monoclinic pyrrhotite (Fe7S8)

Physical Properties of Pyrrhotite

Cleavage:

[0001] Imperfect, [1120] Imperfect

Color:

Bronze, Bronze red, Dark brown.

Density:

4.58 - 4.65, Average = 4.61

Diaphaniety:

Opaque

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Habit:

Platy - Sheet forms (e.g. micas).

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

3.5-4 - Copper Penny-Fluorite

Luminescence:

None.

Luster:

Metallic

Magnetism:

Naturally strong

Streak:

gray black

Optical Properties of Pyrrhotite

RL Anisotrophism:

Strong.

RL Pleochroism:

Weak.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Pyrrhotite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	27.90	31.00
420 nm	28.60	32.20
440 nm	29.40	33.60
460 nm	30.30	34.80
480 nm	31.40	36.20
500 nm	32.40	37.60
520 nm	33.40	38.60
540 nm	34.50	39.60
560 nm	35.50	40.40
580 nm	36.50	41.20
600 nm	37.40	42.00
620 nm	38.30	42.60
640 nm	39.10	43.00
660 nm	39.90	43.50
680 nm	40.70	43.90
700 nm	41.40	44.10

**Calculated Relative Intensity Colors of Pyrrhotite in Air**
Relative Intensity	0%	40%	80%	100%	120%	160%	200%	240%	280%	300%
R₁
R₂

Calculated Properties of Pyrrhotite

Electron Density:

r_electron=3.78 gm/cc
note: r_Pyrrhotite=3.95 gm/cc.

Fermion Index

Fermion Index = 0.01603
Boson Index = 0.98397

Photoelectric:

PE_Pyrrhotite= 20.96 barns/electron
U=PE_Pyrrhotite x r_electron= 79.17 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Pyrrhotite is Not Radioactive

Pyrrhotite Classification

Dana Class:

2.8.10.1 (2)Sulfides - Including Selenides and Tellurides

(2.8)where Am Bn Xp, with (m+n):p=1:1

(2.8.10)Dana Group

2.8.10.1 Pyrrhotite Fe(1-x)S(x=0-0.17) A2/a 2/m

2.8.10.2 Smythite (Fe,Ni)9S11or(Fe,Ni)13S16 R 3m 3 2/m

Strunz Class:

II/C.19-20 II - Sulfides and sulphosalts

II/C - Sulfides with metal: sulfur, selenium and tellurium = 1:1

II/C.19 - Troilite - Pyrrhotite - Haideite series

II/C.19-10 Troilite FeS P 6₃/mmc 6/m 2/m 2/m

II/C.19-20 Pyrrhotite Fe(1-x)S(x=0-0.17) A2/a 2/m

II/C.19-25 Jaipurite* CoS P 6₃/mmc 6/m 2/m 2/m

II/C.19-30 Westerveldite (Fe,Ni,Co)As Pnam 2/m 2/m 2/m

II/C.19-40 Modderite (Co,Fe)As Pmcn 2/m 2/m 2/m

II/C.19-50 Smythite (Fe,Ni)9S11or(Fe,Ni)13S16 R 3m 3 2/m

II/C.19-60 Achavalite* FeSe P 6₃/mmc 6/m 2/m 2/m

II/C.19-70 Heideite (Fe,Cr)1x(Ti,Fe)2S4 I2/m 2/m

Other Pyrrhotite Information

References:

NAME( Sinkankas66) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)

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Pyrrhotite

Fe(1-x)S (x=0-0.17)
Dana No: 2.8.10.1 Strunz No: II/C.19-20
Locality:

Notes: