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The Mineralogy of Iron

General Properties
Symbol:Fe
Atomic Number:26
Standard atomic weight (Ar):55.845(2)
Electron configuration:[Ar] 3d6 4s2
Photos
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Iron electrolytic and 1cm³ cube
>
Atomic Properties
Electronegativity (Pauling scale):1.83
Atomic Radius:156 pm
Ionic Radius:78 pm (+2*)
1st Ionization energy:763 kJ/mol
1st Electron affinity:-16 kJ/mol
Oxidation States:-2,-1,1,2,3,4,5,6
Physical Properties
Standard State:solid
Bonding Type:metallic
Melting Point:1811 K
Boiling Point:3134 K
Density:7.87 g/cm3
Metal/Non-Metal:transition metal
Main isotopes of Iron
Isotope% in NatureHalf LifeDecay typeDecay product
54Fe5.8%>3.1x1022yβ+β+ ?54Cr
55Fesynthetic2.73yε55Mn
56Fe91.72stable
57Fe2.2%Stable
58Fe0.28%stable
59Fesynthetic44.503dβ−59Co
60Fesynthetic2.6x106yβ−60Co
Main ions of Iron
NameIonExample minerals
Iron(II) (Ferrous)Fe2+Siderite
Iron(III) (Ferric)Fe3+Hematite, Goethite
Other Information
Year Discovered:Ancient
Named For:From the Anglo-Saxon: "holy metal", "strong metal"
CPK color coding:#E06633
External Links:WikipediaWebElementsLos Alamos National LaboratoryTheodore Gray's PeriodicTable.com
Simple Compounds and Mineral Names
Nitridesdiiron nitrideFe2N
tetrairon nitrideFe4NRoaldite
Sulfidesiron (II) sulfideFeS+2Troilite, Pyrrhotite
iron persulfideFeS2+2Pyrite, Marcasite
triiron tetrasulfideFe3S4+2,+3Greigite
Selenidesiron selenideFeSe+2
iron perselenideFeSe2+2Ferroselite, Dzharkenite
Telluridesiron tellurideFeTe+2
iron pertellurideFeTe2+2Frohbergite
Hydroxidesiron (II) hydroxideFe(OH)2+2
iron (III) hydroxideFe(OH)3+3Bernalite
iron (III) oxide-hydroxideFeO(OH)+3Goethite, Akaganeite, Lepidocrocite, Feroxyhyte
Fluoridesiron (II) fluorideFeF2+2
iron (III) fluorideFeF3+3
Chloridesiron (II) chlorideFeCl2+2Lawrencite
iron (III) chlorideFeCl3+3Molysite
iron (II) chloride dihydrateFeCl2 · 2H2O+2Rokühnite
Bromidesiron (II) bromide FeBr2
iron (III) bromide FeBr3
IodidesIron (II) diiodide FeI2
Iron (III) iodide FeI3
Oxidesiron (II) oxideFeO+2
iron (iii) oxideFe2O3+3Hematite
triiron tetraoixdeFe3O4+2,+3Magnetite
Carbonatesiron (II) carbonateFeCO3+2Siderite
iron (III) carbonateFe2(CO3)3+3
Nitratesiron (II) nitrateFe(NO3)2+2
iron (III) nitrateFe(NO3)3+3
iron (III) nitrate nonahydrateFe(NO3)3 · 9H2O+3
Sulfatesiron (II) sulfateFeSO4+2
iron (III) sulfateFe2(SO4)3+3Mikasaite
iron (II) sulfate hydrateFeSO4 · H2O+2Szomolnokite
iron (II) sulfate tetrahydrateFeSO4 · 4H2O+2Rozenite
iron (II) sulfate pentahydrateFeSO4 · 5H2O+2Siderotil
iron (II) sulfate hexahydrateFeSO4 · 6H2O+2Ferrohexahydrite
iron (II) sulfate heptahydrateFeSO4 · 7H2O+2Melanterite
iron (III) sulfate pentahydrateFe2(SO4)3 · 5H2O+3Lausenite
iron (III) sulfate heptahydrateFe2(SO4)3 · 7H2O+3Kornelite
iron (III) sulfate nonahydrateFe2(SO4)3 · 9H2O+3Paracoquimbite
iron (III) sulfate undecahydrateFe2(SO4)3 · 11H2O+3Quenstedtite
Iron as a chromophore in minerals and gems
ChromophoreDescription
Fe2+Green colour, eg in forsterite (peridot) and the blue-green colour in phosphophyllite. In some minerals with high concentrations of Fe2+ the colour is brown.
Fe2+ in square planar siteRaspberry red colour in gillespite from El Roasrio, Baja California, Mexico.
Fe2+ in eight-coordinate siteHigher concentrations in pyrope garnet cause a deeper red colour.
Fe3+ in octahedral sitesWhen the Fe3+ ions are isolated by intervening ions it leads to a pale colour, such as the pale purple colour in strengite and coquimbite. Also the yellow-green colour in ferric silicates such as andradite.
Fe3+ in tetrahedral sitesCauses the pale yellow colour in a plagioclase feldspar from Lake County, Oregon.
Fe4+ in deformed tetrahedral silicon positionThe colour in amethyst has been explained as Fe3+ replacing Silicon losing an electron due to radioactive bombardment to become tetravalent Fe4+.
Fe2+ - Fe3+ IVCTIntervalence Charge Transfer between two adjacent metal ions. Usually causes blue-green coloration, examples include rockbridgeite and vivianite.
Fe2+ - Ti4+ IVCTbrown to brownish-red colouration eg in dravite and neptunite (where the reddish tint is more noticeable in thin section.
Mineral Diversity of Iron
1. Elements 32 valid mineral species
2. Sulfides And Sulfosalts 95 valid mineral species
3. Halides11 valid mineral species
4. Oxides 107 valid mineral species
5. Carbonates 10 valid mineral species
6. Borates10 valid mineral species
7. Sulfates 88 valid mineral species
8. Phosphates, Arsenates, Vanadates224 valid mineral species
9. Silicates 243 valid mineral species
10. Organic Compounds3 valid mineral species
Total:823 valid species containing essential Iron
Geochemistry of Iron
Goldschmidt classification:Siderophile
Fe2+ was one of the ions least depleted from the mantle in the formation of the crust.
Fe3+ enters early-forming phases in igneous rocks.
Fe2+ enters early-forming phases in igneous rocks.
Fe3+ is commonly concentrated in residual soils and sediments.
Fe3+ is concentrated in deep-sea ferromanganese nodules relative to seawater.
Fe2+ solute can be a limiting nutrient in the growth of bacteria.
Fe2+ solute can be a limiting nutrient in the oceans.
Fe2+ solute is a micronutrient on land.
Fe2+ is essential to nutrition of at least some vertebrates ('essential minerals').
Elemental Iron in Nature
Found as native element:IronFe
Taenite(Fe,Ni)
Found as natural alloy with Cu:TulameenitePt2CuFe
Found as natural alloy with Pt:IsoferroplatinumPt3Fe
TetraferroplatinumPtFe
Elemental Abundance for Iron
Crust (CRC Handbook)5.63 x 10-2mass fraction, kg/kg
Crust (Kaye & Laby)5.8 x 10-2mass fraction, kg/kg
Crust (Greenwood)6.2000 x 10-2mass fraction, kg/kg
Crust (Ahrens/Taylor)7.07 x 10-2mass fraction, kg/kg
Crust (Ahrens/Wänke)4.92 x 10-2mass fraction, kg/kg
Crust (Ahrens/Weaver)3.8 x 10-2mass fraction, kg/kg
Upper Crust (Ahrens/Taylor)3.50 x 10-2mass fraction, kg/kg
Upper Crust (Ahrens/Shaw)3.09 x 10-2mass fraction, kg/kg
Sea Water (CRC Handbook)2 x 10-9mass per volume fraction, kg/L
Sea Water (Kaye & Laby)3.4 x 10-9mass per volume fraction, kg/L
The Sun (Kaye & Laby)9.0 x 10-1atom mole fraction relative to Si=1
Solar System (Kaye & Laby)9.0 x 10-1atom mole fraction relative to Si=1
Solar System (Ahrens)9.00 x 10-1 (2.7%)atom mole fraction relative to Si=1 (% uncertainty)
Element association of Iron in the Mineral World
This table compares the known valid mineral species listed listed with Iron 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 Iron and the element listed for that row.

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

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 Iron% of Fe mineralsRelative to % in all minerals
Oxygen1060 minerals with Fe and O86.18%11.89% higher
Hydrogen740 minerals with Fe and H60.16%10.90% higher
Silicon413 minerals with Fe and Si33.58%19.94% higher
Calcium312 minerals with Fe and Ca25.37%2.23% higher
Magnesium293 minerals with Fe and Mg23.82%71.56% higher
Aluminium292 minerals with Fe and Al23.74%18.57% higher
Sodium258 minerals with Fe and Na20.98%9.90% higher
Manganese241 minerals with Fe and Mn19.59%68.07% higher
Sulfur239 minerals with Fe and S19.43%1.39% lower
Phosphorus227 minerals with Fe and P18.46%65.76% higher
Titanium162 minerals with Fe and Ti13.17%89.21% higher
Arsenic134 minerals with Fe and As10.89%5.18% lower
Potassium129 minerals with Fe and K10.49%7.37% higher
Copper119 minerals with Fe and Cu9.67%23.40% lower
Zinc92 minerals with Fe and Zn7.48%38.79% higher
Fluorine81 minerals with Fe and F6.59%21.62% lower
Lead80 minerals with Fe and Pb6.50%32.64% lower
Barium66 minerals with Fe and Ba5.37%14.70% higher
Chlorine65 minerals with Fe and Cl5.28%30.44% lower
Nickel59 minerals with Fe and Ni4.80%46.48% higher
Niobium54 minerals with Fe and Nb4.39%28.91% higher
Boron49 minerals with Fe and B3.98%22.30% lower
Cerium45 minerals with Fe and Ce3.66%9.84% higher
Zirconium42 minerals with Fe and Zr3.41%40.37% higher
Antimony39 minerals with Fe and Sb3.17%35.82% lower
Vanadium38 minerals with Fe and V3.09%25.96% lower
Carbon36 minerals with Fe and C2.93%60.80% lower
Strontium35 minerals with Fe and Sr2.85%0.04% higher
Yttrium33 minerals with Fe and Y2.68%1.68% higher
Tin29 minerals with Fe and Sn2.36%27.27% higher
Uranium29 minerals with Fe and U2.36%51.16% lower
Lithium28 minerals with Fe and Li2.28%0.54% higher
Lanthanum26 minerals with Fe and La2.11%22.79% higher
Chromium25 minerals with Fe and Cr2.03%22.04% higher
Beryllium24 minerals with Fe and Be1.95%13.11% lower
Tantalum21 minerals with Fe and Ta1.71%24.98% higher
Bismuth21 minerals with Fe and Bi1.71%58.53% lower
Cobalt21 minerals with Fe and Co1.71%20.05% higher
Molybdenum19 minerals with Fe and Mo1.54%33.14% higher
Tellurium19 minerals with Fe and Te1.54%49.66% lower
Nitrogen17 minerals with Fe and N1.38%28.29% lower
Silver17 minerals with Fe and Ag1.38%58.74% lower
Thorium13 minerals with Fe and Th1.06%17.67% higher
Germanium13 minerals with Fe and Ge1.06%94.76% higher
Tungsten11 minerals with Fe and W0.89%16.57% higher
Thallium10 minerals with Fe and Tl0.81%28.78% lower
Platinum9 minerals with Fe and Pt0.73%14.99% lower
Selenium9 minerals with Fe and Se0.73%68.97% lower
Iridium8 minerals with Fe and Ir0.65%39.03% higher
Neodymium7 minerals with Fe and Nd0.57%41.51% lower
Indium4 minerals with Fe and In0.33%24.13% higher
Rhodium4 minerals with Fe and Rh0.33%8.53% lower
Caesium4 minerals with Fe and Cs0.33%27.59% lower
Scandium3 minerals with Fe and Sc0.24%18.54% lower
Cadmium3 minerals with Fe and Cd0.24%51.73% lower
Ruthenium2 minerals with Fe and Ru0.16%33.16% lower
Mercury2 minerals with Fe and Hg0.16%90.66% lower
Osmium2 minerals with Fe and Os0.16%3.45% lower
Gallium1 mineral with Fe and Ga0.08%37.93% lower
Palladium1 mineral with Fe and Pd0.08%93.97% lower
Gold1 mineral with Fe and Au0.08%85.52% lower
Ytterbium1 mineral with Fe and Yb0.08%27.59% lower
Rhenium1 mineral with Fe and Re0.08%117.24% higher
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 Fe Relative Frequency
Manganese << Iron >> Cobalt


Most widespread minerals containing Iron
This list of minerals containing Iron 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 Iron mineral species. It is more useful when comparing rare species rather than common species.
NameFormulaCrystal SystemMindat Localities
PyriteFeS2Isometric35796
ChalcopyriteCuFeS2Tetragonal25003
MagnetiteFe2+Fe3+2O4Isometric13436
HematiteFe2O3Trigonal12557
ArsenopyriteFeAsSMonoclinic8196
PyrrhotiteFe7S8Monoclinic8183
Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)Monoclinic7520
Goethiteα-Fe3+O(OH)Orthorhombic6641
SideriteFeCO3Trigonal5874
BorniteCu5FeS4Orthorhombic5181
Photos

Localities with greatest number of different Iron mineral species
map should go here
1Clara Mine, Rankach valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany87 Fe minerals
2Hagendorf South Pegmatite (Cornelia Mine; Hagendorf South Open Cut), Hagendorf, Waidhaus, Upper Palatinate, Bavaria, Germany79 Fe minerals
3Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire; MSH), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada72 Fe minerals
4Palermo No. 1 Mine (Palermo No. 1 pegmatite; Hartford Mine; GE Mine), Groton, Grafton Co., New Hampshire, USA67 Fe minerals
5Tsumeb Mine (Tsumcorp Mine), Tsumeb, Otjikoto Region (Oshikoto), Namibia57 Fe minerals
6Långban, Filipstad, Värmland, Sweden55 Fe minerals
7Sapucaia mine (Proberil mine), Sapucaia do Norte, Galiléia, Minas Gerais, Brazil51 Fe minerals
8Foote Lithium Co. Mine (Foote Mine), Kings Mountain District, Cleveland Co., North Carolina, USA50 Fe minerals


Important ores of Iron
NameFormulaCrystal System
HematiteFe2O3Trigonal
Goethiteα-Fe3+O(OH)Orthorhombic
Limonite(Fe,O,OH,H2O)
Photos


Minor ores of Iron
NameFormulaCrystal System
SideriteFeCO3Trigonal
PyriteFeS2Isometric
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)
Mineral and/or Locality  
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