Environmental Chemistry
Environmental chemistry.com: Periodic Table Iridium
Chances are, if you need to know anything about iridium, this site will have it. Exceptionally thorough.
Florida-Spectrum Environmental Services
Florida Spectrum: Chemical Fact Sheet: Iridium
A summary of the basic properties and uses of iridium, as well as a few random facts about it.
Other
Web ref.org: Iridium
A student friendly site with basic information (and links to definitions or examples of key terms) on iridium. Good job on uses.
Web Elements
Web Elements Periodic Table: Iridium
WebElements offers valuable information on iridium, with basic data, chemical and physical properties, electron arrangement and more. A helpful site.
University of Kentucky
Uk: Iridium Comics
A 1968 Metal Men comic strip featuring iridium. Not the greatest source of imformation but good for illustrations and fun.
TED Talks
Ted: Ted Ed: Iridium: Periodic Table of Videos
The team at Periodicvideos has created a TED-Ed Lesson for every element of the periodic table. Iridium is element 77 and its symbol is Ir. [7:08]
Other
Web Mineral/iridium
Very good basic chemical and physical data summary of iridium, as well as a listing (with links to more info and photos) of minerals containing the metal iridium.
Chemicool
Chemicool: Iridium
This site from Chemicool and David D. Hsu is a well organized set of tables summarazing all sorts of helpful information on iridium. A good place to find data on physical properties.
Royal Society of Chemistry
Chemical Society: Iridium
A short summary of iridium's properties and main uses.