Chromium Mineral Data

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:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

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

Diaphaneity:

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:

Bulk Density (Electron Density)=6.65 gm/cc
note: Specific Gravity of Chromium =7.20 gm/cc.

Fermion Index:

Fermion Index = 0.09
Boson Index = 0.91

Photoelectric:

PE_Chromium= 23.26 barns/electron
U=PE_Chromium x rElectron Density= 154.63 barns/cc.

Radioactivity:

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

Chromium Classification

Dana Class:

01.01.12.01 (01)Native Elements

(01.01)with metallic elements other than the platinum group

(01.01.12)Dana Group

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

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

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

Strunz Class:

01.AE.05 01 - ELEMENTS (Metals and intermetallic alloys; metalloids and nonmetals; carbides, silicides, nitrides, phosphides)

01.A - Metals and Intermetallic Alloys

01.AE -Iron-chromium family

01.AE.05 Chromium Cr I m3m 4/m 3 2/m

01.AE.05 Kamacite? alpha-(Fe,Ni) F m3m 4/m 3 2/m

01.AE.05 Iron Fe I m3m 4/m 3 2/m

Other Chromium Information

References:

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

See Also:

Links to other databases for Chromium :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - GeoScienceWorld
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - Mineralienatlas (Deutsch)
11 - Online Mineral Museum
12 - QUT Mineral Atlas
13 - Ruff.Info
14 - WWW-MINCRYST

Search for Chromium using:

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Mineral News Website Link
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Ask about Chromium here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Chromium

Cr
Dana No: 01.01.12.01 Strunz No: 01.AE.05
Locality:

Notes: