Cohenite Mineral Data

General Cohenite Information

Chemical Formula:

(Fe,Ni,Co)3C

Composition:

Molecular Weight = 183.04 gm

Iron 54.92 % Fe

Cobalt 9.66 % Co

Nickel 28.86 % Ni

Carbon 6.56 % C

______

100.00 %

Empirical Formula:

Fe⁰⁺_1.8Ni_0.9Co_0.3C

Environment:

In iron meteorites, also in terrestrial iron, in mafic rocks chemically reduced from the assimilation of graphite.

IMA Status:

Valid Species (Pre-IMA) 1889

Locality:

Common in iron meteorites. Link to MinDat.org Location Data.

Name Origin:

Named for Emil Wilhelm Cohen (1842-1905), Professor of Mineralogy, University of Greifswald, Greifswald, Germany.

Synonym:

ICSD 16593

PDF 35-772

Cohenite Image

Images:

Cohenite

Comments: Bluish gray, metallic iridescent crystals of cohenite on matrix.
Location: Kopeisk, Chelyabinsk Oblast', Urals Region, Russia. Scale: 2.3 mm.
© Thomas Witzke / Abraxas-Verlag

Images:

Cohenite Troilite Kamacite Taenite

Comments: Brown masses of troilite, with white cohenite, in kamacite/taenite matrix, in meteorite (polished section).
Location: Meteor Crater, Canyon Diablo, Coconino County, Arizona, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Cohenite Crystallography

Axial Ratios:

a:b:c =0.8913:1:1.3288

Cell Dimensions:

a = 4.518, b = 5.069, c = 6.736, Z = 4; V = 154.27 Den(Calc)= 7.88

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pbnm

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

By Intensity(I/I_o): 2.01(1), 2.06(0.7), 2.38(0.65),

Crystal Structure:

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Hendricks B S , Zeitschrift fur Kristallographie , 74 (1930) p.534-545, The crystal structure of cementite

Physical Properties of Cohenite

Cleavage:

{???} Good, {???} Good, {???} Good

Color:

Yellowish white.

Density:

7.2 - 7.65, Average = 7.42

Diaphaneity:

Opaque

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Hardness:

5.5-6 - Knife Blade-Orthoclase

Luster:

Metallic

Magnetism:

Strongly magnetic

Optical Properties of Cohenite

RL Color:

Tin-white.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Cohenite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	51.80	54.70
420 nm	52.60	55.20
440 nm	53.20	55.70
460 nm	53.80	56.20
480 nm	54.40	56.70
500 nm	55.00	57.10
520 nm	55.60	57.70
540 nm	56.20	58.20
560 nm	56.80	58.80
580 nm	57.40	59.30
600 nm	58.00	60.00
620 nm	58.70	60.60
640 nm	59.30	61.30
660 nm	60.00	62.00
680 nm	60.80	62.80
700 nm	61.60	63.60

**Calculated Relative Intensity Colors of Cohenite in Air**
Relative Intensity	0%	20%	40%	60%	80%	100%	120%	140%	160%	170%
R₁
R₂

Calculated Properties of Cohenite

Electron Density:

Bulk Density (Electron Density)=7.41 gm/cc
note: Specific Gravity of Cohenite =7.88 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Cohenite= 32.09 barns/electron
U=PE_Cohenite x rElectron Density= 237.86 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Cohenite is Not Radioactive

Cohenite Classification

Dana Class:

01.01.16.01 (01)Native Elements

(01.01)with metallic elements other than the platinum group

(01.01.16)Dana Group

01.01.16.01 Cohenite (Fe,Ni,Co)3C Pbnm 2/m 2/m 2/m

01.01.16.02 Haxonite (Fe,Ni)23C6 F m3m 4/m 3 2/m

01.01.16.03 Isovite! (Cr,Fe)23C6 F m3m 4/m 3 2/m

Strunz Class:

01.BA.05 01 - ELEMENTS (Metals and intermetallic alloys; metalloids and nonmetals; carbides, silicides, nitrides, phosphides)

01.B - Metallic Carbides, Silicides, Nitrides and Phosphides

01.BA -Carbides

01.BA.05 Cohenite (Fe,Ni,Co)3C Pbnm 2/m 2/m 2/m

Other Cohenite Information

References:

NAME( AntBidBlaNic3) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic3)

See Also:

Links to other databases for Cohenite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Ask about Cohenite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Cohenite Specimen Label here :

Cohenite

(Fe,Ni,Co)3C
Dana No: 01.01.16.01 Strunz No: 01.BA.05
Locality:

Notes: