iridium [Ir]

Introduction

From the Latin iris meaning rainbow. Discovered with osmium in 1803 by English chemist Smithson Tennant in residue obtained from dissolving platinum.

Occurrence

• found in platinum ores & as a by-product of mining nickel

Characteristics

• silver-white hard brittle very heavy metallic element
• iridium is the most corrosion-resistant metal known
• iridium salts are highly colored
• forms cations Ir+ & Ir+3

Uses

• alloys: used as a hardening agent for platinum
• helicopter spark plugs

More general terms

• chemical element
• metal

Additional terms

• periodic table

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=23924