Details : Item 215

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Alkali metals
Alkaline earth metal
Transition metals I
Transition metals II
Transition metals III
Transition metals IV
Post-transition metal
Metalloid
Diatomic non-metal
Noble gas
Other

Famille : Transition metals III/6
Iridium
Symbol: Ir, phase: solid, silvery white. One of the rarest
elements in Earth s crust, with annual production of only
3t.An alloy of 90% platinum and 10% iridium was used in
1889 to construct the International Prototype Metre.
Properties
Atomic number77
Atomic weight192.217
Melting point (K)2719
Boiling point (K)4403
Speed of sound (m/s)4825
Discovery1803 (S. Tennant)