Iridosmine - Encyclopedia

    Class : Elements
    Subclass : Metals
    Crystal system : Hexagonal
    Chemistry : Os,Ir
    Rarity : Rare

Iridosmine (or iridosmium) is a natural alloy of osmium (approximately 56%) and iridium (approximately 43%). It belongs to the group of platinum minerals of which it has an extreme density (around 20) and a tin-white color with a bluish tint. Like other platinum minerals, iridosmine is present in iron-nickel sulfide horizons of certain mafic stratified complexes, but has mainly been recovered in platinum-bearing sands. Its name was given to it in reference to its chemical composition. It occurs in sub-rounded to tumbled grains, rarely in flattened hexagonal lamellar crystals. It is an ore of osmium and iridium.

Main photo : Iridosmine from the Neiva River alluvium, Sverdlovsk Oblast, Russia © Yuan Xue - SEM image

Iridosmine in the World

Iridosmine sands are known and exploited in Russia (Inagli, near Aldan), Australia (Adamsfield and Heazlewood), Canada (Atlin and Princeton in British Columbia), Japan, Sierra Leone... Crystals of museological quality, however, remain to be discovered.

Iridosmine in France

In France, iridosmine has been reported in the alluvium of the Durance (Bouches-du-Rhône).


No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.

Hardness : 6 to 7
Density : 22.5
Fracture : Undeterminated
Streak : Gray

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : Insoluble

Magnetism : NoneRadioactivity : None


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