Magnesiochromite Mineral Data

Magnesiochromite Mineral Data +

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General Magnesiochromite Information

Chemical Formula:

MgCr2O4

Composition:

Molecular Weight = 192.29 gm

Magnesium 12.64 % Mg 20.96 % MgO

Chromium 54.08 % Cr 79.04 % Cr₂O₃

Oxygen 33.28 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

MgCr₂O₄

IMA Status:

Valid Species (Pre-IMA) 1868

Locality:

Link to MinDat.org Location Data.

Synonym:

Chrompicotite

ICSD 20819

PDF 10-351

Magnesiochromite Image

Images:

Magnesiochromite

Comments: Black crystalline magnesiochromite grains in serpentinite.
Location: Red Pit, Fulton Township, Lancaster County, Pennsylvania, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Magnesiochromite Crystallography

Cell Dimensions:

a = 8.277, Z = 8; V = 567.05 Den(Calc)= 4.50

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): 2.49(1), 1.466(0.7), 1.593(0.6),

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Crystal Structure:

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Lenaz D , Princivalle F , The Canadian Mineralogist , 43 (2005) p.1305-1314, The crystal chemistry of detrital chromian spinel from the, southeastern Alps and Outer Dinarides: The discrimination of, supplies from areas of similar tectonic setting?, Sample: BG 17B

View Additional jPOWD Structure files for Magnesiochromite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [3] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [4] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [5] [50] [51] [52] [53] [54] [55] [56] [57] [58] [6] [7] [8] [9]

Physical Properties of Magnesiochromite

Cleavage:

None

Color:

Black.

Density:

4.2

Diaphaniety:

Opaque

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Hardness:

5.5 - Knife Blade

Luster:

Metallic

Streak:

dark gray

Optical Properties of Magnesiochromite

Optical Data:

NCalc= 2.22 - from Gladstone-Dale relationship (KC = 0.2711) where Ncalc=Dcalc*KC+1
NCalc= 2.14 - from Gladstone-Dale relationship (KC = 0.2711) where Ncalc=Dmeas*KC+1

Calculated Properties of Magnesiochromite

Electron Density:

r_electron=4.31 gm/cc
note: r_{Magnesiochromite}=4.50 gm/cc.

Fermion Index

Fermion Index = 0.06417
Boson Index = 0.93583

Photoelectric:

PE_{Magnesiochromite}= 12.54 barns/electron
U=PE_{Magnesiochromite} x r_electron= 54.01 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Magnesiochromite is Not Radioactive

Magnesiochromite Classification

Dana Class:

7.2.3.1 (7)Multiple Oxides

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

(7.2.3)(Chromium subgroup)

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

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

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

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

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

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

Strunz Class:

IV/B.03-10 IV - Oxides

IV/B - Oxides with metal : oxygen = 3:4 (spinel type M3O4 and related) Chromite-Spinels

IV/B.03 - Spinel group, Magnesio-chromite - Zinco-chromite series

IV/B.03-10 Magnesiochromite MgCr2O4 F d3m 4/m 3 2/m

IV/B.03-20 Chromite FeCr2O4 F d3m 4/m 3 2/m

IV/B.03-30 Manganochromite (Mn,Fe)(Cr,V)2O4 F d3m 4/m 3 2/m

IV/B.03-40 Cochromite (Co,Ni,Fe)(Cr,Al)2O4 F d3m 4/m 3 2/m

IV/B.03-50 Nichromite (Ni,Co,Fe)(Cr,Fe,Al)2O4 F d3m 4/m 3 2/m

IV/B.03-60 Zincochromite ZnCr2O4 F d3m 4/m 3 2/m

Other Magnesiochromite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)

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

Magnesiochromite

MgCr2O4
Dana No: 7.2.3.1 Strunz No: IV/B.03-10
Locality:

Notes: