Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Magnesiochromite

This page is currently not sponsored. Click here to sponsor this page.
Formula:
MgCr23+O4
System:
Isometric
Colour:
Black, deep red
Lustre:
Greasy, Metallic, Sub-Metallic
Hardness:
Member of:
Name:
Named by Antoine François Alfred Lacroix in 1910 in allusion to the composition, containing MAGNESIum and its relationship to CHROMITE. The mineral was originally named magnochromite by G. M. von Bock in 1868.
Isostructural with:
Spinel Group, Cr subgroup. Chromite-Magnesiochromite Series and Magnesiochromite-Spinel Series. It forms a complete solid solution series with many other members of the group. It is the magnesium analogue of zincochromite, cochromite, manganochromite and chromite and the Cr analogue of spinel and magnesioferrite.

It usually contains ferrous iron [Fe(II)], ferric iron [Fe(III)], and Al. "Ferritchromite", i.e. Fe(III) substitutions for Al and Cr, usually in grain rims, may give high total Fe and a false chromite identification, whereas Fe(II)> Mg is the actual deciding factor in the species designation for chromite. Magnesiochomite is about twice as common as chromite.

Much of the mineral referred to as "chromite" in geological and petrological papers and mining statistics is magnesiochromite. The Fe-dominant species chromite may be subordinate to magnesiochromite in many "chromite" deposits, chromitites, and other "chromite"-bearing rocks.

Note: Chromite, that is near end-member, has a higher specific gravity than near end-member magnesiochromite.


Classification of Magnesiochromite

Approved, 'Grandfathered' (first described prior to 1959)
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
7.2.3.1

7 : MULTIPLE OXIDES
2 : AB2X4
7.14.13

7 : Oxides and Hydroxides
14 : Oxides of Cr

Physical Properties of Magnesiochromite

Greasy, Metallic, Sub-Metallic
Diaphaneity (Transparency):
Opaque
Colour:
Black, deep red
Streak:
Brown
Hardness (Mohs):
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
Parting may be present on {111}
Fracture:
Irregular/Uneven, Hackly, Sub-Conchoidal
Comment:
Broken surfaces may have an angular granulated appearance
Density:
4.1 - 4.3 g/cm3 (Measured)    4.43 g/cm3 (Calculated)
Comment:
Large crystals of "chomite" may be distinguished by specific gravity.

Optical Data of Magnesiochromite

Type:
Isotropic
Type:
Isotropic
Pleochroism:
Non-pleochroic

Chemical Properties of Magnesiochromite

IMA Formula:
MgCr23+O4
Mindat.org Formula:
MgCr2O4

Mg may be partially replaced by divalent Fe, and Cr by Al and trivalent Fe.
Elements listed in formula:
Common Impurities:
Fe,Al

Crystallography of Magnesiochromite

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fd3m
Cell Parameters:
a = 8.305Å
Unit Cell Volume:
V 572.82 ų (Calculated from Unit Cell)
Morphology:
Crystals may be octahedral, sometimes modified by {001}, etc. Commonly massive.
X-Ray Powder Diffraction Data:
d-spacingIntensity
4.81 (60)
2.95 (10)
2.51 (100)
2.08 (50)
1.60 (40)
1.47 (50)
1.41 (10)
Comments:
ICDD 10-351 (synthetic)

Type Occurrence of Magnesiochromite

Relationship of Magnesiochromite to other Species

Series:
Forms a series with Spinel (see here)
Forms a series with Chromite (see here)
Member of:
Other Members of Group:
ChromiteFe2+Cr23+O4
Cochromite(Co,Ni,Fe)(Cr,Al)2O4
CoulsoniteFe2+V23+O4
CuprospinelCu2+Fe23+O4
Filipstadite(Sb0.5Fe0.5)Mn2O4
FrankliniteZn2+Fe23+O4
GahniteZnAl2O4
GalaxiteMn2+Al2O4
HercyniteFe2+Al2O4
JacobsiteMn2+Fe23+O4
MagnesiocoulsoniteMgV2O4
MagnesioferriteMgFe23+O4
MagnetiteFe2+Fe23+O4
ManganochromiteMn2+Cr2O4
Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
Qandilite(Mg,Fe3+)2(Ti,Fe3+,Al)O4
SpinelMgAl2O4
TrevoriteNi2+Fe23+O4
UlvöspinelFe2TiO4
VuorelaineniteMn2+V23+O4
XieiteFe2+Cr2O4
ZincochromiteZnCr2O4
4.BB.05ChromiteFe2+Cr2O4
4.BB.05CochromiteCoCr2O4
4.BB.05CoulsoniteFe2+V23+O4
4.BB.05CuprospinelCu2+Fe23+O4
4.BB.05Filipstadite(Mn2+,Mg)2(Sb5+,Fe3+)O4
4.BB.05FrankliniteZnFe23+O4
4.BB.05GahniteZnAl2O4
4.BB.05GalaxiteMn2+Al2O4
4.BB.05HercyniteFe2+Al2O4
4.BB.05JacobsiteMn2+Fe23+O4
4.BB.05ManganochromiteMn2+Cr2O4
4.BB.05MagnesiocoulsoniteMgV2O4
4.BB.05MagnesioferriteMgFe23+O4
4.BB.05MagnetiteFe2+Fe23+O4
4.BB.05Nichromite(Ni,Co,Fe)(Cr,Fe,Al)2O4
4.BB.05QandiliteMg2(Ti,Fe3+,Al)O4
4.BB.05SpinelMgAl2O4
4.BB.05TrevoriteNiFe23+O4
4.BB.05UlvöspinelFe22+TiO4
4.BB.05VuorelaineniteMn2+V23+O4
4.BB.05ZincochromiteZnCr2O4
4.BB.10HausmanniteMn2+Mn23+O4
4.BB.10HetaeroliteZnMn23+O4
4.BB.10HydrohetaeroliteHZnMn3+5/3O4
4.BB.10IwakiiteMn2+Fe23+O4
4.BB.15MaghemiteFe2.67O4
4.BB.15TitanomaghemiteFe(Fe,Ti)2O4
4.BB.20TegengreniteMg2(Sb,Mn)O4
4.BB.25XieiteFeCr2O4
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(Mg,Cr,Fe,Ca,K)2(Ti,Zr,Cr,Fe)5O12
7.14.7McconnelliteCu1+CrO2
7.14.8RedledgeiteBa(Ti64+Cr23+)O16
7.14.9HawthorneiteBaMgTi3Cr4Fe22+Fe23+O19
7.14.10ZincochromiteZnCr2O4
7.14.11WattersiteHg41+Hg2+O2(CrO4)
7.14.12ChromiteFe2+Cr2O4

Other Names for Magnesiochromite

Other Information

Not fluorescent in UV
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Magnesiochromite

Reference List:
von Bock, G. M. (1868) Inaugual Dissertation, Beslau.

Websky, W. (1873) Zeitschrift Deutchland Geol. Gesselschaft, 25:394.

Dana, System of Mineralogy, Sixth ed. (1892): 228.

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

Fisher (1929), American Mineralogist: 14: 355 (as Magnochromite).

Betekhtin (1934), Ann. Inst. Mines, Leningrad: 8: 38 (as Ferrichromsinel).

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.

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

O'Neill, H.St.C. and Dollase, W.A. (1994) Crystal structures and cation distribution in simple spinels from powder XRD structural refinements: MgCr2O4, ZnCr2O4, Fe3O4, and the temperature dependence of the cation distribution in ZnAl2O4. Physics and Chemistry of Minerals: 20: 541-555.

Internet Links for Magnesiochromite

mindat.org URL:
https://www.mindat.org/min-2493.html
Please feel free to link to this page.

Localities for Magnesiochromite

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.
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2017, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: March 26, 2017 08:18:13 Page generated: March 24, 2017 07:18:02
Go to top of page