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Chromite

This page kindly sponsored by Jake Slagle
Formula:
Fe2+Cr23+O4
System:
Isometric
Colour:
Black
Hardness:
Member of:
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:
Isostructural with:
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

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
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
7.2.3.3

7 : MULTIPLE OXIDES
2 : AB2X4
7.14.12

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

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

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:
4.5 - 4.8 g/cm3 (Measured)    5.12 g/cm3 (Calculated)

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}

Crystallographic forms of Chromite

Crystal Atlas:
Image Loading
Click on an icon to view
Chromite no.1 - Goldschmidt (1913-1926)
Chromite no.2 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

Toggle
Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction Data:
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
Max 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:
Fe2+Cr23+O4
Idealised Formula:
FeCr2O4
Essential elements:
All elements listed in formula:
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:
Other Members of Group:
Ceylonite
Cochromite(Co,Ni,Fe)(Cr,Al)2O4
CoulsoniteFe2+V23+O4
CuprospinelCu2+Fe23+O4
Filipstadite(Sb0.5Fe0.5)Mn2O4
FrankliniteZn2+Fe23+O4
GahniteZnAl2O4
Galaxite(Mn,Fe,Mg)(Al,Fe)2O4
HercyniteFe2+Al2O4
JacobsiteMn2+Fe23+O4
MagnesiochromiteMg(Cr,Al,Fe)2O4
MagnesiocoulsoniteMgV2O4
MagnesioferriteMgFe23+O4
MagnetiteFe2+Fe23+O4
Manganochromite(Mn,Fe)(Cr,V)2O4
Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
Qandilite(Mg,Fe)2(Ti,Fe,Al)O4
SpinelMgAl2O4
TrevoriteNi2+Fe23+O4
UlvöspinelFe2TiO4
Vuorelainenite(Mn,Fe)(V,Cr)2O4
ZincochromiteZnCr2O4
4.BB.05Cochromite(Co,Ni,Fe)(Cr,Al)2O4
4.BB.05CoulsoniteFe2+V23+O4
4.BB.05CuprospinelCu2+Fe23+O4
4.BB.05Filipstadite(Sb0.5Fe0.5)Mn2O4
4.BB.05FrankliniteZn2+Fe23+O4
4.BB.05GahniteZnAl2O4
4.BB.05Galaxite(Mn,Fe,Mg)(Al,Fe)2O4
4.BB.05HercyniteFe2+Al2O4
4.BB.05JacobsiteMn2+Fe23+O4
4.BB.05Manganochromite(Mn,Fe)(Cr,V)2O4
4.BB.05MagnesiocoulsoniteMgV2O4
4.BB.05MagnesiochromiteMg(Cr,Al,Fe)2O4
4.BB.05MagnesioferriteMgFe23+O4
4.BB.05MagnetiteFe2+Fe23+O4
4.BB.05Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
4.BB.05Qandilite(Mg,Fe)2(Ti,Fe,Al)O4
4.BB.05SpinelMgAl2O4
4.BB.05TrevoriteNi2+Fe23+O4
4.BB.05UlvöspinelFe2TiO4
4.BB.05Vuorelainenite(Mn,Fe)(V,Cr)2O4
4.BB.05ZincochromiteZnCr2O4
4.BB.10HausmanniteMn2+Mn23+O4
4.BB.10HetaeroliteZnMn2O4
4.BB.10HydrohetaeroliteZnMn2O4 · H2O
4.BB.10IwakiiteMn2+Fe23+O4
4.BB.15MaghemiteFe23+O3
4.BB.15TitanomaghemiteFe3+(Fe3+,Ti4+,Fe2+,◻)2O4
4.BB.20Tegengrenite(Mg,Mn2+)2Sb5+0.5(Mn3+,Si,Ti)0.5O4
4.BB.25XieiteFe2+Cr2O4
7.14.1EskolaiteCr2O3
7.14.2BracewelliteCrO(OH)
7.14.3GrimaldiiteCrO(OH)
7.14.4GuyanaiteCrO(OH)
7.14.5YimengiteK(Cr,Ti,Fe,Mg)12O19
7.14.6Mathiasite(K, Ba, Sr)(Zr, Fe)(Mg,Fe)2 (Ti,Cr,Fe)18O38
7.14.7McconnelliteCuCrO2
7.14.8RedledgeiteBa(Ti64+Cr23+)O16
7.14.9HawthorneiteBa(MgTi3Cr4Fe4)O19
7.14.10ZincochromiteZnCr2O4
7.14.11Wattersite(Hg2+)2Hg2+(CrO4)O2
7.14.13MagnesiochromiteMg(Cr,Al,Fe)2O4

Other Names for Chromite

Other Information

Not fluorescent in UV
Other Information:
Some are weakly magnetic due to zones of magnetite composition, etc.
Health Risks:
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

Localities for Chromite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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