Cochromite Mineral Data

General Cochromite Information

Chemical Formula:

(Co,Ni,Fe++)(Cr,Al)2O4

Composition:

Molecular Weight = 207.97 gm

Magnesium 1.17 % Mg 1.94 % MgO

Aluminum 5.19 % Al 9.81 % Al₂O₃

Chromium 35.00 % Cr 51.16 % Cr₂O₃

Iron 8.06 % Fe 6.91 % FeO / 3.84 % Fe₂O₃

Cobalt 14.17 % Co 18.01 % CoO

Nickel 5.64 % Ni 7.18 % NiO

Oxygen 30.77 % O

______ ______

100.00 % 98.85 % = TOTAL OXIDE

Empirical Formula:

Co_0.5Ni_0.2Fe²⁺_0.2Mg_0.1Cr_1.4Al_0.4Fe³⁺_0.1O₄

Environment:

Replacing chromite in a small tabular nickel deposit in a contact between quartzite and serpentinized ultramafics.

IMA Status:

Approved IMA 1978

Locality:

Bon Accord deposit, Barberton, Transvaal, South Africa. Link to MinDat.org Location Data.

Name Origin:

Named for a chromite with essential cobalt.

Synonym:

ICSD 69503

PDF 22-1084

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Cochromite Crystallography

Cell Dimensions:

a = 8.292, Z = 8; V = 570.14 Den(Calc)= 4.85

Crystal System:

Isometric - HexoctahedralH-M Symbol (4/m 3 2/m) Space Group: F d3m

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

By Intensity(I/I_o): 2.512(1), 1.4721(0.45), 2.947(0.35),

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Forms: ( 1 1 1)

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Crystal Structure:

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Garcia Casado P , Rasines I , Polyhedron , 5 (1986) p.787-789, Preparation and crystal data of the spinel series Co1+2sCr2-3sSb3O4, Sample: s = 0.40, Co1.8Cr.8Sb.4O4

Physical Properties of Cochromite

Cleavage:

{???} Indistinct

Color:

Black.

Density:

5.22

Diaphaneity:

Opaque

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Hardness:

7 - Quartz

Luster:

Metallic

Streak:

green

Optical Properties of Cochromite

Optical Data:

NCalc= 2.18 - from Gladstone-Dale relationship (KC = 0.2425) where Ncalc=Dcalc*KC+1
NCalc= 2.27 - from Gladstone-Dale relationship (KC = 0.2425) where Ncalc=Dmeas*KC+1

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Cochromite in Air**
λ	R	∑ R(λ)
480 nm	14.30
546 nm	13.70
589 nm	14.00
656 nm	13.90

**Calculated Relative Intensity Colors of Cochromite in Air**
Relative Intensity	0%	70%	100%	140%	210%	280%	350%	420%	490%	560%	630%
R

Calculated Properties of Cochromite

Electron Density:

Bulk Density (Electron Density)=4.61 gm/cc
note: Specific Gravity of Cochromite =4.85 gm/cc.

Fermion Index:

Fermion Index = 0.03
Boson Index = 0.97

Photoelectric:

PE_Cochromite= 17.80 barns/electron
U=PE_Cochromite x rElectron Density= 82.11 barns/cc.

Radioactivity:

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

Cochromite Classification

Dana Class:

07.02.03.05 (07)Multiple Oxides

(07.02)(A+ B++)2 X4 Spinel group

(07.02.03)(Chromium subgroup)

07.02.03.01 Magnesiochromite MgCr2O4 F d3m 4/m 3 2/m

07.02.03.02 Manganochromite (Mn,Fe)(Cr,V)2O4 F d3m 4/m 3 2/m

07.02.03.03 Chromite FeCr2O4 F d3m 4/m 3 2/m

07.02.03.04 Nichromite (Ni,Co,Fe)(Cr,Fe,Al)2O4 F d3m 4/m 3 2/m

07.02.03.05 Cochromite (Co,Ni,Fe)(Cr,Al)2O4 F d3m 4/m 3 2/m

07.02.03.06 Zincochromite ZnCr2O4 F d3m 4/m 3 2/m

Strunz Class:

04.BB.05 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.B - Metal:Oxygen = 3:4 and similar

04.BB -With only medium-sized cations

04.BB.05 Cochromite (Co,Ni,Fe)(Cr,Al)2O4 F d3m 4/m 3 2/m

04.BB.05 Filipstadite (Mn,Mg)4SbFeO8 pseudo ISO 2/m 2/m 2/m

04.BB.05 Magnetite FeFe2O4 F d3m 4/m 3 2/m

04.BB.05 Gahnite ZnAl2O4 F d3m 4/m 3 2/m

04.BB.05 Chromite FeCr2O4 F d3m 4/m 3 2/m

04.BB.05 Galaxite (Mn,Mg)(Al,Fe)2O4 F d3m 4/m 3 2/m

04.BB.05 Cuprospinel (Cu,Mg)Fe2O4 F d3m 4/m 3 2/m

04.BB.05 Donathite? (Fe,Mg)(Cr,Fe)2O4 P 4/nnm 4/m 2/m 2/m

04.BB.05 Brunogeierite (Ge,Fe)Fe2O4 F d3m 4/m 3 2/m

04.BB.05 Coulsonite FeV2O4 F d3m 4/m 3 2/m

04.BB.05 Hercynite FeAl2O4 F d3m 4/m 3 2/m

04.BB.05 Franklinite (Zn,Mn,Fe)(Fe,Mn)2O4 F d3m 4/m 3 2/m

04.BB.05 Jacobsite (Mn,Fe,Mg)(Fe,Mn)2O4 F d3m 4/m 3 2/m

04.BB.05 Magnesiochromite MgCr2O4 F d3m 4/m 3 2/m

04.BB.05 Magnesioferrite MgFe2O4 F d3m 4/m 3 2/m

04.BB.05 Magnesiocoulsonite MgV2O4 F d3m 4/m 3 2/m

04.BB.05 Manganochromite (Mn,Fe)(Cr,V)2O4 F d3m 4/m 3 2/m

04.BB.05 Qandilite (Mg,Fe)2(Ti,Fe,Al)O4 F d3m 4/m 3 2/m

04.BB.05 Nichromite (Ni,Co,Fe)(Cr,Fe,Al)2O4 F d3m 4/m 3 2/m

04.BB.05 Spinel MgAl2O4 F d3m 4/m 3 2/m

04.BB.05 Ulvospinel TiFe2O4 F d3m 4/m 3 2/m

04.BB.05 Zincochromite ZnCr2O4 F d3m 4/m 3 2/m

04.BB.05 Trevorite NiFe2O4 F d3m 4/m 3 2/m

04.BB.05 Vuorelainenite (Mn,Fe)(V,Cr)2O4 F d3m 4/m 3 2/m

Other Cochromite Information

References:

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

See Also:

Links to other databases for Cochromite :
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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Print or Cut-and-Paste your Cochromite Specimen Label here :

Cochromite

(Co,Ni,Fe++)(Cr,Al)2O4
Dana No: 07.02.03.05 Strunz No: 04.BB.05
Locality:

Notes: