Definition
Iridium is a hard, brittle, corrosion-resistant metal with the symbol 77Ir192. It is one of the platinum group elements (PGE – ruthenium, rhodium, palladium, rhenium, osmium, iridium, platinum), which are highly siderophilic and form strong bonds with iron. Most of the terrestrial PGE are concentrated in the core, leaving the mantle and crust highly depleted in Ir (ca. 3 and <0.05 ppb, respectively). In comparison, undifferentiated meteorites are enriched in PGE (ca. 200–500 ppb). Elevated PGE concentrations measured in terrestrial rocks indicate a meteoritic contribution. The detection of the iridium enrichment in the KT boundary clay layer first led to the meteoritic impact hypothesis as a possible cause of the dinosaur extinction. The determination of PGE elemental ratios in impactites can contribute to the identification of the type of impacted meteorite.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2014 Springer-Verlag Berlin Heidelberg
About this entry
Cite this entry
Claeys, P. (2014). Iridium. In: Amils, R., et al. Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27833-4_808-3
Download citation
DOI: https://doi.org/10.1007/978-3-642-27833-4_808-3
Received:
Accepted:
Published:
Publisher Name: Springer, Berlin, Heidelberg
Online ISBN: 978-3-642-27833-4
eBook Packages: Springer Reference Physics and AstronomyReference Module Physical and Materials ScienceReference Module Chemistry, Materials and Physics