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The Mineralogy of Chromium

General Properties
Symbol:Cr
Atomic Number:24
Standard atomic weight (Ar):51.9961(6)
Electron configuration:[Ar] 3d5 4s1
Photos
<
Chromium
>
Atomic Properties
Electronegativity (Pauling scale):1.66
Atomic Radius:166 pm
Ionic Radius:80 pm (+2*)
1st Ionization energy:653 kJ/mol
1st Electron affinity:-64 kJ/mol
Oxidation States:-2,-1,1,2,3,4,5,6
Physical Properties
Standard State:solid
Bonding Type:metallic
Melting Point:2180 K
Boiling Point:2944 K
Density:7.14 g/cm3
Metal/Non-Metal:transition metal
Main isotopes of Chromium
Isotope% in NatureHalf LifeDecay typeDecay product
50Cr4.345%>1.3x1018yβ+β+ ?50Ti
51Crsynthetic27.7025dε51V
52Cr83.789%stable
53Cr9.501%stable
54Cr2.365%stable
Main ions of Chromium
NameIonExample minerals
chromium(III)Cr3+Eskolaite
chromate[CrO4]2-Crocoite
dichromate[Cr2O7]2-
Other Information
Year Discovered:Ancient
Year Isolated:1798
Isolated By:
Louis Nicolas Vauquelin
Named For:From Greek: chróma - "color"
CPK color coding:#8A99C7
External Links:WikipediaWebElementsLos Alamos National LaboratoryTheodore Gray's PeriodicTable.com
Simple Compounds and Mineral Names
Nitrideschromium nitrideCrN+3Carlsbergite
Sulfideschromium sulphideCrS+2
dichromium trisulphideCr2S3+3
trichromium tetrasulphideCr3S4+2,+3Brezinaite
pentachromium hexasulphideCr5S6Murchisite
Selenideschromium selenideCrSe+2
Telluridesdichromium tritellurideCr2Te3+3
Hydroxideschromium oxide hydroxideCrOOH+3Bracewellite, Grimaldiite, Guyanaite
Fluorideschromium difluorideCrF2+2
chromium trifluorideCrF3+3
chromium tetrafluorideCrF4+4
chromium pentafluorideCrF5+5
chromium hexafluorideCrF6+6
Chlorideschromium dichlorideCrCl2+2
chromium trichlorideCrCl3+3
chromium tetrachlorideCrCl4+4
Bromideschromium dibromideCrBr2
chromium tribromideCrBr3
chromium tetrabromideCrBr4
Iodideschromium diiodideCrI2+2
chromium triiodideCrI3+3
chromium tetraiodideCrI4+4
Oxideschromium dioxideCrO2+4
chromium trioxideCrO3+6
dichromium trioxideCr2O3+3Eskolaite
trichromium tetroxideCr3O4+2,+3
Carbonateschromium (II) carbonateCrCO3+2
chromium (III) carbonateCr2(CO3)3+3
Nitrateschromium (III) nitrateCr(NO)3+3
chromium (III) nitrate nonahydrate[Cr(H2O)6](NO3)3 · 3H2O+3
Sulfateschromium (II) sulfate pentahydrateCrSO4 · 5H2O+2
chromium (III) sulfateCr2(SO4)3+3
chromium (III) sulfate dodecahydrateCr2(SO4)3 · 12H2O+3
Chromium as a chromophore in minerals and gems
ChromophoreDescription
Cr3+Gives green colour in most emeralds, grossular eg from the Jeffrey Mine in Quebec, Canada, Jadeite etc. Gives red colour in spinel and ruby
Mineral Diversity of Chromium
1. Elements 8 valid mineral species
2. Sulfides And Sulfosalts 8 valid mineral species
3. Halides1 valid mineral species
4. Oxides 19 valid mineral species
5. Carbonates 2 valid mineral species
6. Borates1 valid mineral species
7. Sulfates 19 valid mineral species
9. Silicates 13 valid mineral species
Total:71 valid species containing essential Chromium
Geochemistry of Chromium
Goldschmidt classification:Lithophile
Cr3+ was one of the ions least depleted from the mantle in the formation of the crust.
Cr3+ enters early-forming phases in igneous rocks.
Cr3+ is commonly concentrated in residual soils and sediments.
Cr3+ is essential to nutrition of at least some vertebrates ('essential minerals').
Elemental Chromium in Nature
Found as native element:ChromiumCr
Found as natural alloy with Fe:FerchromideCr3Fe1-x
ChromferideFe3Cr1-x (x=0.6)
Elemental Abundance for Chromium
Crust (CRC Handbook)1.02 x 10-4mass fraction, kg/kg
Crust (Kaye & Laby)9.6 x 10-5mass fraction, kg/kg
Crust (Greenwood)1.22 x 10-4mass fraction, kg/kg
Crust (Ahrens/Taylor)1.85 x 10-4mass fraction, kg/kg
Crust (Ahrens/Wänke)1.46 x 10-4mass fraction, kg/kg
Crust (Ahrens/Weaver)5.6 x 10-5mass fraction, kg/kg
Upper Crust (Ahrens/Taylor)3.5 x 10-5mass fraction, kg/kg
Upper Crust (Ahrens/Shaw)3.5 x 10-5mass fraction, kg/kg
Sea Water (CRC Handbook)3 x 10-10mass per volume fraction, kg/L
Sea Water (Kaye & Laby)2 x 10-10mass per volume fraction, kg/L
The Sun (Kaye & Laby)1.3 x 10-2atom mole fraction relative to Si=1
Solar System (Kaye & Laby)1.3 x 10-2atom mole fraction relative to Si=1
Solar System (Ahrens)1.35 x 10-2 (7.6%)atom mole fraction relative to Si=1 (% uncertainty)
Element association of Chromium in the Mineral World
This table compares the known valid mineral species listed listed with Chromium and the other elements listed based on the official IMA formula. Note that unlike other sections on this page this includes non-essential elements.

The first data column contains the total number of minerals listed with Chromium and the element listed for that row.

The second data column lists this number as a percentage of all minerals listed with Chromium.

The final data column compares this percentage against the percentage of all minerals that contain the element listed in each row.

Click on a heading to sort.
ElementValid Minerals listed with element and Chromium% of Cr mineralsRelative to % in all minerals
Oxygen73 minerals with Cr and O82.02%6.49% higher
Hydrogen37 minerals with Cr and H41.57%23.36% lower
Iron25 minerals with Cr and Fe28.09%22.04% higher
Magnesium21 minerals with Cr and Mg23.60%69.94% higher
Silicon18 minerals with Cr and Si20.22%27.75% lower
Lead18 minerals with Cr and Pb20.22%109.46% higher
Sulfur15 minerals with Cr and S16.85%14.47% lower
Calcium13 minerals with Cr and Ca14.61%41.13% lower
Titanium13 minerals with Cr and Ti14.61%109.83% higher
Sodium12 minerals with Cr and Na13.48%29.36% lower
Aluminium10 minerals with Cr and Al11.24%43.88% lower
Copper8 minerals with Cr and Cu8.99%28.84% lower
Vanadium8 minerals with Cr and V8.99%115.41% higher
Potassium7 minerals with Cr and K7.87%19.48% lower
Carbon6 minerals with Cr and C6.74%9.71% lower
Strontium5 minerals with Cr and Sr5.62%97.52% higher
Manganese5 minerals with Cr and Mn5.62%51.81% lower
Zinc5 minerals with Cr and Zn5.62%4.24% higher
Barium5 minerals with Cr and Ba5.62%20.09% higher
Boron5 minerals with Cr and B5.62%9.57% higher
Phosphorus4 minerals with Cr and P4.49%59.63% lower
Fluorine3 minerals with Cr and F3.37%59.88% lower
Mercury3 minerals with Cr and Hg3.37%93.69% higher
Uranium3 minerals with Cr and U3.37%30.18% lower
Zirconium3 minerals with Cr and Zr3.37%38.57% higher
Yttrium3 minerals with Cr and Y3.37%27.76% higher
Chlorine3 minerals with Cr and Cl3.37%55.63% lower
Bismuth2 minerals with Cr and Bi2.25%45.41% lower
Cerium2 minerals with Cr and Ce2.25%32.53% lower
Arsenic2 minerals with Cr and As2.25%80.44% lower
Nickel2 minerals with Cr and Ni2.25%31.38% lower
Iodine2 minerals with Cr and I2.25%380.36% higher
Lanthanum1 mineral with Cr and La1.12%34.73% lower
Nitrogen1 mineral with Cr and N1.12%41.70% lower
Molybdenum1 mineral with Cr and Mo1.12%3.15% lower
Cobalt1 mineral with Cr and Co1.12%20.99% lower
Niobium1 mineral with Cr and Nb1.12%67.01% lower
Beryllium1 mineral with Cr and Be1.12%49.96% lower
Antimony1 mineral with Cr and Sb1.12%77.26% lower
Tellurium1 mineral with Cr and Te1.12%63.39% lower
Periodic Table
1H 2He
3Li 4Be 5B 6C 7N 8O 9F 10Ne
11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar
19K 20Ca 21Sc 22Ti 23V 24Cr 25Mn 26Fe 27Co 28Ni 29Cu 30Zn 31Ga 32Ge 33As 34Se 35Br 36Kr
37Rb 38Sr 39Y 40Zr 41Nb 42Mo 43Tc 44Ru 45Rh 46Pd 47Ag 48Cd 49In 50Sn 51Sb 52Te 53I 54Xe
55Cs 56Ba 57La 72Hf 73Ta 74W 75Re 76Os 77Ir 78Pt 79Au 80Hg 81Tl 82Pb 83Bi 84Po 85At 86Rn
87Fr 88Ra 89Ac 104Rd 105Db 106Sg 107Bh 108Hs 109Mt 110Ds 111Rg 112Cn 113Nh 114Fl 115Mc 116Lv 117Ts 118Og
 
58Ce 59Pr 60Nd 61Pm 62Sm 63Eu 64Gd 65Tb 66Dy 67Ho 68Er 69Tm 70Yb 71Lu
90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97Bk 98Cf 99Es 100Fm 101Md 102No 103Lr
Default Categories CPK Electronegativity Atomic Radius Lowest Oxidation Highest Oxidation Crustal Abundance Goldschmidt Mineral Species Minerals with Cr Relative Frequency
Vanadium << Chromium >> Manganese


Most widespread minerals containing Chromium
This list of minerals containing Chromium is built from the mindat.org locality database. This is based on the number of localities entered for mineral species and is therefore slanted towards minerals interesting to collectors with less coverage of common rock-forming-minerals so it does not give an undistorted distribution of Chromium mineral species. It is more useful when comparing rare species rather than common species.
NameFormulaCrystal SystemMindat Localities
ChromiteFe2+Cr3+2O4Isometric3376
MagnesiochromiteMgCr2O4Isometric288
UvaroviteCa3Cr2(SiO4)3Isometric208
DaubréeliteFe2+Cr3+2S4Isometric148
CrocoitePb(CrO4)Monoclinic86
FornacitePb2Cu(CrO4)(AsO4)(OH)Monoclinic84
VauquelinitePb2Cu(CrO4)(PO4)(OH)Monoclinic64
StichtiteMg6Cr2(OH)16[CO3] · 4H2OTrigonal44
PhoenicochroitePb2(CrO4)OMonoclinic37
EskolaiteCr2O3Trigonal27
Photos

Localities with greatest number of different Chromium mineral species
map should go here
1Pereval Marble Quarry, Slyudyanka (Sludyanka), Lake Baikal area, Irkutskaya Oblast', Prebaikalia (Pribaikal'e), Eastern-Siberian Region, Russia12 Cr minerals
2Mammoth-Saint Anthony Mine (Mammoth-St Anthony Mine; Mammoth Mine; St. Anthony Mine), St. Anthony deposit, Tiger, Mammoth District, Pinal Co., Arizona, USA8 Cr minerals
3Berezovskoe Au Deposit (Berezovsk Mines), Berezovskii (Berezovskii Zavod), Ekaterinburg (Sverdlovsk), Sverdlovskaya Oblast', Middle Urals, Urals Region, Russia7 Cr minerals
4Red Lead Mine, Dundas mineral field, Zeehan district, West Coast municipality, Tasmania, Australia7 Cr minerals
Callenberg North open cut (No. 1), Callenberg, Glauchau, Saxony, Germany6 Cr minerals
6Hatrurim Formation, Negev, Israel5 Cr minerals
7Merume river, Kamakusa, Mazaruni District, Guyana5 Cr minerals
8Norton County meteorite, Norton Co., Kansas, USA5 Cr minerals


Important ores of Chromium
NameFormulaCrystal System
ChromiteFe2+Cr3+2O4Isometric
MagnesiochromiteMgCr2O4Isometric
Photos


Other significant minerals containing Chromium
NameFormulaCrystal System
CrocoitePb(CrO4)Monoclinic
UvaroviteCa3Cr2(SiO4)3Isometric
Photos


Spotted a mistake/omission? - These pages are a work in progress, so please send all comments/corrections to jolyon@mindat.org. Thank you.

Constants and physical property data from:

David R. Lide (ed.), CRC Handbook of Chemistry and Physics, 85th Edition. CRC Press. Boca Raton, Florida (2005).
Kaye and Laby Tables of Physical & Chemical Constants (2005). Section 3.1.3, Abundances of the elements
A. Earnshaw, N. Greenwood, Chemistry of the Elements, 2nd edition, Butterworth-Heinemann, (1997)
Thomas J. Ahrens (ed.), Global Earth Physics : A Handbook of Physical Constants, American Geophysical Union (1995)
L.B. Railsback, An Earth Scientist's Periodic Table of the Elements and Their Ions : Geology 31:9 p737-740 (2003)
Emsley, J. Nature's Building Blocks: An A-Z Guide to the Elements. New York: Oxford University Press (2001)
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