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Chromite

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Formula:
Fe
2+
 
Cr
3+
2
O
 
4
System:IsometricColour:Black
Hardness:
Member of:Spinel Group
Name:Chromite was named in 1845 by Wilhelm Haidinger n allusion to its composition. The species was originally named fer chromate alumine by Louis Nicolas Vauquelin in 1798. Vauquelin was the discoverer of the element chromium.
Dimorph of:Xieite
Isostructural with:Magnesiochromite, Magnetite


Spinel Group. It apparently forms a complete solid solution series with many other members of the group, eg. in the Chromite-Hercynite Series, Chromite-Spinel Series, Chromite-Magnetite Series and the Chromite-Magnesiochromite Series. It is the iron analogue of Zincochromite, Cochromite, Manganochromite and Magnesiochromite and the Cr analogue of Hercynite, Coulsonite and Magnetite

It usually contains Mg, ferric iron [Fe(III)], Al and often Ti. "Ferrichromite", i.e. Fe(III) substitutions for Al and Cr, usually in grain rims, may give high total Fe contents and a false chromite identification. Of course, the definition requires dominant Fe(II)>Mg and Cr>Fe(III). (e.g. photo ID: 514894).

"Chromite" is commonly used for any Cr-rich mineral of the spinel group, particularly for the chromite-magnesiochromite series, and much of the mineral referred to as "chromite" in geological and petrological papers and mining statistics is usually Magnesiochromite. The Fe-dominant species - Chromite itself - can be FOUND, although uncommonly, in many "chromite" deposits, chromitite (rock name), and other "chromite"-bearing occurrences connected with hyperbasic rocks. As a rule of thumb, a member of the chromite-magnesiochromite series is twice as likely to be a magnesiochromite instead of a chromite. "Chromites" associated with olivine or serpentines, which are Mg-rich rocks, frequently have Mg-rich associated minerals. True chromite is common as inclusions in Diamonds from kimberlites (South Africa and Yakutia). Members of the spinel group may be enriched Cr and V in marbles (Slyudyanka), massive sulphide ores (Outokumpu) and also in some types of meteorites. In any case, "chromite" always needs ANALYTICAL CONFIRMATION. Note: Chromite, that is near end-member, has a higher specific gravity than near end-member magnesiochromite.

Classification of Chromite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:4/B.03-20
Nickel-Strunz 10th (pending) edition ID:4.BB.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
B : With only medium-sized cations
Dana 8th edition ID:7.2.3.3

7 : MULTIPLE OXIDES
2 : AB2X4
Hey's CIM Ref.:7.14.12

7 : Oxides and Hydroxides
14 : Oxides of Cr
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Type Occurrence of Chromite

Type Locality:Bastide de la Carrade, Gassin, Var, Provence-Alpes-Côte d'Azur, France
Year of Discovery:1845

Occurrences of Chromite

Geological Setting:As a cumulate mineral layer in ultramafic igneous rocks, in peridotites. As placer deposits. Common in meteorites except carbonaceous chondrites.

Physical Properties of Chromite

Lustre:Resinous, Greasy, Metallic, Sub-Metallic, Dull
Diaphaneity (Transparency):Opaque
Colour:Black
Streak:Brown
Hardness (Mohs):
Hardness (Vickers):VHN100=1278 - 1456 kg/mm2
Tenacity:Brittle
Cleavage:None Observed
Parting:Parting may develop along {111}
Fracture:Irregular/Uneven, Hackly, Sub-Conchoidal
Comment:Broken surfaces frequently have an angular granulated appearance.
Density (measured):4.5 - 4.8 g/cm3
Density (calculated):5.12 g/cm3

Crystallography of Chromite

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Fd3m
Space Group Setting:Fd3m
Cell Parameters:a = 8.344Å
Unit Cell Volume:V 580.93 ų (Calculated from Unit Cell)
Z:8
Morphology:Octahedral crystals uncommon, modified by {001} at times. Rarely, crystals may show small dodecahedral faces, etc. Usually massive, fine granular to compact.
Twinning:On {111}
Crystal Atlas:
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Chromite no.1 - Goldschmidt (1913-1926)
Chromite no.2 - Goldschmidt (1913-1926)

About Crystal Atlas

The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. The 3d models and HTML5 code are kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

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Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction:
d-spacingIntensity
4.84 (10)
2.96 (30)
2.53 (100)
2.09 (20)
1.61 (40)
1.48 (50)
1.09 (10)
0.855 (10)
Comments:ICDD 34-140 (synthetic). See also GSAM 85:195 (1962) natural material.

Optical Data of Chromite

Type:Isotropic
RI values: n = 2.08 - 2.16
Birefringence:0.0
Maximum Birefringence:δ = 0.000 - Isotropic minerals have no birefringence
Surface Relief:Very High
Type:Isotropic
Colour in reflected light:Grey-white with brownish tint.
Internal Reflections:Brownish red
Pleochroism:Non-pleochroic

Chemical Properties of Chromite

Formula:
Fe
2+
 
Cr
3+
2
O
 
4
Simplified for copy/paste:Fe2+Cr3+2O4
Idealised Formula:
FeCr
 
2
O
 
4
Essential elements:Cr, Fe, O
All elements listed in formula:Cr, Fe, O
Common Impurities:Mg,Mn,Zn,Al,Ti

Relationship of Chromite to other Species

Series:Forms a series with Hercynite (see here)
Forms a series with Magnesiochromite (see here)
Forms a series with Magnetite (see here)
Member of:Spinel Group
Other Members of Group:

- +
Ceylonite
Cochromite
(Co,Ni,Fe)(Cr,Al)
 
2
O
 
4
Coulsonite
Fe
2+
 
V
3+
2
O
 
4
Cuprospinel
Cu
2+
 
Fe
3+
2
O
 
4
Filipstadite
(Sb
 
0.5
Fe
 
0.5
)Mn
 
2
O
 
4
Franklinite
Zn
2+
 
Fe
3+
2
O
 
4
Gahnite
ZnAl
 
2
O
 
4
Galaxite
(Mn,Fe,Mg)(Al,Fe)
 
2
O
 
4
Hercynite
Fe
2+
 
Al
 
2
O
 
4
Jacobsite
Mn
2+
 
Fe
3+
2
O
 
4
Magnesiochromite
Mg(Cr,Al,Fe)
 
2
O
 
4
Magnesiocoulsonite
MgV
 
2
O
 
4
Magnesioferrite
MgFe
3+
2
O
 
4
Magnetite
Fe
2+
 
Fe
3+
2
O
 
4
Manganochromite
(Mn,Fe)(Cr,V)
 
2
O
 
4
Nichromite
(Ni,Co,Fe)(Cr,Fe,Al)
 
2
O
 
4
Qandilite
(Mg,Fe)
 
2
(Ti,Fe,Al)O
 
4
Spinel
MgAl
 
2
O
 
4
Trevorite
Ni
2+
 
Fe
3+
2
O
 
4
Ulvöspinel
Fe
 
2
TiO
 
4
Vuorelainenite
(Mn,Fe)(V,Cr)
 
2
O
 
4
Zincochromite
ZnCr
 
2
O
 
4
Related Minerals - Nickel-Strunz Grouping):

- +
4.BB.05Cochromite
(Co,Ni,Fe)(Cr,Al)
 
2
O
 
4
4.BB.05Coulsonite
Fe
2+
 
V
3+
2
O
 
4
4.BB.05Cuprospinel
Cu
2+
 
Fe
3+
2
O
 
4
4.BB.05Filipstadite
(Sb
 
0.5
Fe
 
0.5
)Mn
 
2
O
 
4
4.BB.05Franklinite
Zn
2+
 
Fe
3+
2
O
 
4
4.BB.05Gahnite
ZnAl
 
2
O
 
4
4.BB.05Galaxite
(Mn,Fe,Mg)(Al,Fe)
 
2
O
 
4
4.BB.05Hercynite
Fe
2+
 
Al
 
2
O
 
4
4.BB.05Jacobsite
Mn
2+
 
Fe
3+
2
O
 
4
4.BB.05Manganochromite
(Mn,Fe)(Cr,V)
 
2
O
 
4
4.BB.05Magnesiocoulsonite
MgV
 
2
O
 
4
4.BB.05Magnesiochromite
Mg(Cr,Al,Fe)
 
2
O
 
4
4.BB.05Magnesioferrite
MgFe
3+
2
O
 
4
4.BB.05Magnetite
Fe
2+
 
Fe
3+
2
O
 
4
4.BB.05Nichromite
(Ni,Co,Fe)(Cr,Fe,Al)
 
2
O
 
4
4.BB.05Qandilite
(Mg,Fe)
 
2
(Ti,Fe,Al)O
 
4
4.BB.05Spinel
MgAl
 
2
O
 
4
4.BB.05Trevorite
Ni
2+
 
Fe
3+
2
O
 
4
4.BB.05Ulvöspinel
Fe
 
2
TiO
 
4
4.BB.05Vuorelainenite
(Mn,Fe)(V,Cr)
 
2
O
 
4
4.BB.05Zincochromite
ZnCr
 
2
O
 
4
4.BB.10Hausmannite
Mn
2+
 
Mn
3+
2
O
 
4
4.BB.10Hetaerolite
ZnMn
 
2
O
 
4
4.BB.10Hydrohetaerolite
ZnMn
 
2
O
 
4
· H
 
2
O
4.BB.10Iwakiite
Mn
2+
 
Fe
3+
2
O
 
4
4.BB.15Maghemite
Fe
3+
2
O
 
3
4.BB.15Titanomaghemite
Fe
3+
 
(Fe
3+
 
,Ti
4+
 
,Fe
2+
 
,◻)
 
2
O
 
4
4.BB.20Tegengrenite
(Mg,Mn
2+
 
)
 
2
Sb
5+
0.5
(Mn
3+
 
,Si,Ti)
 
0.5
O
 
4
4.BB.25Xieite
Fe
2+
 
Cr
 
2
O
 
4
Related Minerals - Hey's Index Grouping:

- +
7.14.1Eskolaite
Cr
 
2
O
 
3
7.14.2Bracewellite
CrO(OH)
7.14.3Grimaldiite
CrO(OH)
7.14.4Guyanaite
CrO(OH)
7.14.5Yimengite
K(Cr,Ti,Fe,Mg)
 
12
O
 
19
7.14.6Mathiasite
(K, Ba, Sr)(Zr, Fe)(Mg,Fe)
 
2
(Ti,Cr,Fe)
 
18
O
 
38
7.14.7Mcconnellite
CuCrO
 
2
7.14.8Redledgeite
Ba(Ti
4+
6
Cr
3+
2
)O
 
16
7.14.9Hawthorneite
Ba(MgTi
 
3
Cr
 
4
Fe
 
4
)O
 
19
7.14.10Zincochromite
ZnCr
 
2
O
 
4
7.14.11Wattersite
(Hg
+
2
)
 
2
Hg
2+
 
(CrO
 
4
)O
 
2
7.14.13Magnesiochromite
Mg(Cr,Al,Fe)
 
2
O
 
4

Other Names for Chromite

Synonyms:
Autunite (of Leymerie)Beresofite (of Simpson)Chromate of IronChromic IronChromoferrite
Chrompicotite (of Lacroix)EisenchromeFerrochromateFerrochromiteSiderochrome
Other Languages:
Basque:Kromita
Czech:Chromit
Dutch:Chromiet
Esperanto:Kromito
Finnish:Kromiitti
French:Chromite
Fer chromaté
Fer chromaté aluminé
Fer chromé
German:Chromit
Chromeisenerz
Chromeisenspinell
Chromeisenstein
Chromoferrit
Chromsaures Eisen
Cromit
Eisenchrom
Ferrochromit
Hebrew:כרומיט
Hungarian:Kromit
Italian:Cromite
Cromoferrite
Ferro cromato
Siderocromo
Japanese:クロム鉄鉱
Lithuanian:Chromitas
Low Saxon:Chromit
Polish:Chromit
Portuguese:Cromita
Romanian:Cromit
Russian:Хромит
Simplified Chinese:铬铁矿
Spanish:Cromita
Cromoferrita
Ferrochromita
Hierro cromado
Swedish:Kromit
Chromjernmalm
Ukrainian:Хроміт
Varieties:
Aluminian ChromiteAlumoberezoviteBerezovskiteChromferritFerrian Chromite
FerrichromiteTitaniferous Chromite

Other Information

Fluorescence in UV light:Not fluorescent in UV
Other Information:Some are weakly magnetic due to zones of magnetite composition, etc.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:Major ore source for chromium.

References for Chromite

Reference List:

- +
Vauqueline (1800), Bull. soc. philom.: 55: 57.

Pemberton, H. (1891), Chromite: Chem. News: 63: 241.

Simpson (1920), Mineralogical Magazine: 19: 99 (as Beresofite).

Palache, Charles, Harry Berman & Clifford Frondel (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: 709-712.

Bliss, N.W. and MacLean, W.H. (1975) The paragenesis of zoned chromite from central Manitoba. Geochimica et Cosmochimica Acta: 39: 973-990.

Da Silva, E.G., Abras, A., and Sette Camara, A.O.R. (1976) Mössbauer effect study of cation distribution in natural chromites. Journal of Applied Physics: 12: 783-785.

Fatseas, G.A., Dormann, J.L., and Blanchard, H. (1976) Study of the Fe 3+ / Fe 2+ ratio in natural chromites (Fe x Mg 1-x)(Cr 1-y-x Fe y Al z)O4. Journal of Physics: 12: 787-792.

Da Silva, E.G., Abras, A., and Speziali, L. (1980) Mössbauer effect study of cation distribution in natural chromites of Brazilian and Philippine origin. Journal of Applied Physics: 12: 389-392.

Osborne, M.D., Fleet, M.E., and Bancroft, G.M. (1981) Fe 2+ - Fe 3+ ordering in chromite and Cr-bearing spinels. Contributions to Mineralogy and Petrology: 77: 251-255.

Mitra, S., PAl, T., and Pal, T. (1991) Petrogenic implication of the Mössbauer hyperfine parameters of Fe 3+-chromites from Sukinda (India) ultramafites. Mineralogical Magazine: 55(4): 535:542.

Chen, Y.L., Xu, B.F., Chen, J.G., and ge, Y.Y. (1992) Fe 2+ - Fe 3+ ordered distribution in chromite spinels. Physics and Chemistry of Minerals: 19(4): 255-259.

Leblanc, M. and Ceuleneer, G. (1992) Chromite crystallisation in multicelular magma flow: evidence from a chromitite dike in the Oman ophiolite. Lithos: 27: 231-257.

Canadian Mineralogist (1994): 32: 729-746.

Zhou, Mei-Fu, Robinson, P.T., and Bai, W.J. (1994) Formartion of podiform chromitites by melt/rock interaction in the upper mantle. Mineral. Deposita: 29: 98-101.

Zhou, Mei-Fu, Robinson, P.T., Malpas, J., and Li, Z. (1996) Podiform chromitites in the Luobusa ophiolite (southern Tibet): implications for melt-rock interaction and chromite segregation in the upper mantle. Journal of Petrology: 37: 3-21.

Figueiras, J. and Waerenborgh, J.C. (1997) Fully oxidized chromite in the Serra Alta (South Portugal) quartzites: chemical and structural characterization and geological implications. Mineralogical Magazine: 61: 627-638.

Zhou, Mei-Fu and Robnson, P.T. (1997) Origin and tectonic environment of podiform chromite deposits. Economic geology: 92: 259-262.

Zhou, Mei-Fu, Sun, Min, Keays, R.R., and Kerrich, R.W. (1998) Controls on platinum-group elemental distributions of podiform chromitites: a case study of high-Cr and high-Al chromitites from Chinese orogenic belts. Geochimica et Cosmochimica Acta: 62: 677-688.

Barnes, S.J. (2000) Chromite in komatiites. II. Modification during greenschist to mid-amphibolite facies metamorphism. Journal of Petrology: 41: 387-409.

Salviulo, G., Carbonin, S., and Della Giusta, A. (2000) Powder and single-crystal X-ray structural refinements on a natural chromite: dependence of site occupancies on experimental strategies. Materials Science Forum: 321-324: 46-52.

Papike, J.J., Karner, J.M., and Shearer, C.K. (2004) Comparative planetary mineralogy: V/(Cr+Al) systematics in chromite as an indicator of relative oxygen fugacity. American Mineralogist: 89: 1557-1560.

Mosier, D.L., Singer, D.A., Moring, B.C., and Galloway, J.P., (2012), Podiform chromite deposits—database and grade and tonnage models: U.S. Geological Survey Scientific Investigations Report 2012–5157, 45 p. and database.

Internet Links for Chromite

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  • Localities for Chromite

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