Iridium foil. — Photo: Dschwen · CC BY 2.5
Iridium
The second-densest metal on Earth (symbol Ir, atomic number 77) — a hard, brittle platinum-group element found in placer alloys and meteorites.
Intro adapted from Wikipedia (CC BY-SA).
Iridium is an IMA-recognized mineral species in the native element class, with the chemical formula Ir.
It crystallizes in the cubic crystal system (space group Fm3m). It is a member of the Copper structural group.
Key properties: Mohs hardness 6–7; specific gravity 22.65–22.84; Very high metallic. R: (400) 67.4, (420) 68.1, (440) 68.8, (460) 69.3, (480) 69.6, (500) 69.9, (520) 70.2, (540) 70.7 luster.
IMA symbol Ir, IMA status: approved, named in 1804.
Occurs as exsolution particles in Pt–Fe alloys.
It is found associated with Platinum, Pt–Fe alloys.
The name comes from the Latin iris, rainbow, as the element’s compounds are typically highly colored.