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The Mineralogy of Iridium

General Properties
Atomic Number:77
Standard atomic weight (Ar):192.217(3)
Electron configuration:[Xe] 4f14 5d7 6s2
One troy ounce (31.1035 g) of arc-melted iridium
Atomic Properties
Electronegativity (Pauling scale):2.2
Atomic Radius:180 pm
Ionic Radius:68 pm (+3)
1st Ionization energy:880 kJ/mol
1st Electron affinity:-151 kJ/mol
Oxidation States:-3,-1,1,2,3,4,5,6
Physical Properties
Standard State:solid
Bonding Type:metallic
Melting Point:2739 K
Boiling Point:4701 K
Density:22.56 g/cm3
Metal/Non-Metal:transition metal
Main isotopes of Iridium
Isotope% in NatureHalf LifeDecay typeDecay product
191Ir37.3%-α ?187Re
192m2Irsynthetic241yIsomeric transition192Ir
193Ir62.7%-α ?189Re
193mIrsynthetic10.5dIsomeric transition193Ir
194m2Irsynthetic171dIsomeric transition194Ir
Main ions of Iridium
NameIonExample minerals
Other Information
Year Discovered:1803
Discovered By:
Smithson Tennant
Year Isolated:1803
Isolated By:Smithson Tennant
Named For:
The Greek goddess Iris
CPK color coding:#175487
External Links:WikipediaWebElementsLos Alamos National LaboratoryTheodore Gray's PeriodicTable.com
Simple Compounds and Mineral Names
Sulfidesiridium disulphideIrS2+4
diiridium trisulphideIr2S3+3Kashinite
Selenidesiridium diselenideIrSe2+4
Telluridesiridium ditellurideIrTe2+4Shuangfengite
Fluoridesiridium trifluorideIrF3+3
iridium hexafluorideIrF6+6
iridium tetrafluorideIrF4+4
iridium pentafluoride tetramer[IrF5]4+5
Chloridesiridium dichlorideIrCl2+2
iridium trichlorideIrCl3+3
iridium tetrachlorideIrCl4+4
Bromidesiridium tribromideIrBr3+3
iridium tetrabromideIrBr4+4
Iodidesiridium diiodideIrI2+2
iridium triiodideIrI3+3
iridium tetraiodideIrI4+4
Oxidesiridium dioxideIrO2+4
diiridium trioxideIr2O3+3
iridium oxide dihydrateIrO2 · 2H2O+4
Mineral Diversity of Iridium
1. Elements 3 valid mineral species
2. Sulfides And Sulfosalts 11 valid mineral species
Total:14 valid species containing essential Iridium
Geochemistry of Iridium
Goldschmidt classification:Siderophile
Ir4+ is enriched in Ca-Al-rich inclusions in meteorites relative to the composition of the solar system.
Elemental Abundance for Iridium
Crust (CRC Handbook)1 x 10-9mass fraction, kg/kg
Crust (Kaye & Laby)2 x 10-10mass fraction, kg/kg
Crust (Greenwood)1 x 10-9mass fraction, kg/kg
Crust (Ahrens/Taylor)1 x 10-10mass fraction, kg/kg
Crust (Ahrens/Wänke)1.02 x 10-9mass fraction, kg/kg
Upper Crust (Ahrens/Taylor)2 x 10-11mass fraction, kg/kg
The Sun (Kaye & Laby)6.0 x 10-7atom mole fraction relative to Si=1
Solar System (Kaye & Laby)6.6 x 10-7atom mole fraction relative to Si=1
Solar System (Ahrens)6.61 x 10-7 (6.1%)atom mole fraction relative to Si=1 (% uncertainty)
Element association of Iridium in the Mineral World
This table compares the known valid mineral species listed listed with Iridium 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 Iridium and the element listed for that row.

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

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 Iridium% of Ir mineralsRelative to % in all minerals
Sulfur33 minerals with Ir and S50.77%143.90% higher
Iron20 minerals with Ir and Fe30.77%41.00% higher
Ruthenium18 minerals with Ir and Ru27.69%12,516.15% higher
Rhodium18 minerals with Ir and Rh27.69%8,805.52% higher
Copper17 minerals with Ir and Cu26.15%100.26% higher
Platinum17 minerals with Ir and Pt26.15%3,985.23% higher
Osmium11 minerals with Ir and Os16.92%11,464.81% higher
Tellurium9 minerals with Ir and Te13.85%342.67% higher
Lead9 minerals with Ir and Pb13.85%36.15% higher
Nickel6 minerals with Ir and Ni9.23%200.38% higher
Arsenic6 minerals with Ir and As9.23%24.23% lower
Bismuth6 minerals with Ir and Bi9.23%117.52% higher
Molybdenum3 minerals with Ir and Mo4.62%271.06% higher
Antimony3 minerals with Ir and Sb4.62%5.85% 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 Ir Relative Frequency
Osmium << Iridium >> Platinum

Most widespread minerals containing Iridium
This list of minerals containing Iridium 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 Iridium mineral species. It is more useful when comparing rare species rather than common species.
NameFormulaCrystal SystemMindat Localities

Localities with greatest number of different Iridium mineral species
map should go here
2Gaositai Cr-PGE deposit (Gao District; Gaotai village), Gaositai, Chengde Co., Chengde, Hebei, China8 Ir minerals
4Wulie river placers, Chengde Co., Chengde, Hebei, China6 Ir minerals
8Uktus complex, Yekaterinburg, Sverdlovsk Oblast, Russia5 Ir minerals
7Fox Gulch (Fox Gulch Platinum placer), Salmon River - Red Mountain District, Goodnews Bay, Bethel Census Area, Alaska, USA5 Ir minerals

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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