Chromium Mineral Data

Chromium Mineral Data

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General Chromium Information

Chemical Formula:

Composition:

Molecular Weight = 52.00 gm

Chromium 100.00 % Cr

______

100.00 %

Empirical Formula:

Environment:

In heavy sands derived from the contact metamorphic zone between a siliceous marble and ultramafic rock.

IMA Status:

Approved IMA 1981

Locality:

Sichuan Province, China. Link to MinDat.org Location Data.

Name Origin:

From the Greek, chroma = "color", in allusion to the colorful salts of this element.

Synonym:

ICSD 64711

PDF 6-694

Chromium Image

Images:

Chromium

Comments: Small silvery-gray metallic grain of native chromium.
Location: Sichuan, China. Scale: Grain size 0.7 mm.
© Thomas Witzke / Abraxas-Verlag

Chromium Crystallography

Cell Dimensions:

a = 2.8839, Z = 2; V = 23.99 Den(Calc)= 7.20

Crystal System:

Isometric - HexoctahedralH-M Symbol (4/m 3 2/m) Space Group: I m3m

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

By Intensity(I/I_o): 2.039(1), 1.177(0.3), 0.912(0.2),

Crystal Structure:

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Wyckoff R W G , Crystal Structures , 1 (1963) p.7-83, Second edition. Interscience Publishers, New York, New York, Cubic closest packed, ccp, structure

View Additional jPOWD Structure files for Chromium
[1] [2]

Physical Properties of Chromium

Color:

White.

Density:

7.2

Diaphaniety:

Opaque

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Hardness:

7.5 - Garnet

Luster:

Metallic

Optical Properties of Chromium

RL Color:

White with a yellow tint.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Chromium in Air**
λ	R	∑ R(λ)
480 nm	65.30
546 nm	67.90
589 nm	68.80
656 nm	70.00

**Calculated Relative Intensity Colors of Chromium in Air**
Relative Intensity	0%	20%	40%	60%	80%	100%	120%	140%
R

Calculated Properties of Chromium

Electron Density:

r_electron=6.65 gm/cc
note: r_Chromium=7.20 gm/cc.

Fermion Index

Fermion Index = 0.095
Boson Index = 0.905

Photoelectric:

PE_Chromium= 23.26 barns/electron
U=PE_Chromium x r_electron= 154.63 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Chromium is Not Radioactive

Chromium Classification

Dana Class:

1.1.12.1 (1)Native Elements

(1.1)with metallic elements other than the platinum group

(1.1.12)Dana Group

1.1.12.1 Chromium Cr I m3m 4/m 3 2/m

1.1.12.2 Chromferide Fe3Cr1-x(x=0,6) P m3m 4/m 3 2/m

1.1.12.3 Ferchromide Cr3Fe1-x(x=0,6) P m3m 4/m 3 2/m

Strunz Class:

I/A.06-10 I - Elements

I/A - Metallic and intermetallic compounds, Carbides, Nitrides, Phosphides and Silicides

I/A.06 - Chromium series, Titanium-Chromferides

I/A.06-05 Titanium* Ti P 6₃/mmc 6/m 2/m 2/m

I/A.06-10 Chromium Cr I m3m 4/m 3 2/m

I/A.06-20 Ferchromide Cr3Fe1-x(x=0,6) P m3m 4/m 3 2/m

I/A.06-30 Chromferide Fe3Cr1-x(x=0,6) P m3m 4/m 3 2/m

Other Chromium Information

References:

NAME( AntBidBlaNic1) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

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Chromium

Cr
Dana No: 1.1.12.1 Strunz No: I/A.06-10
Locality:

Notes: