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Website
Environmental Chemistry

Environmental chemistry.com: Periodic Table Iridium

For Students 9th - 10th
Chances are, if you need to know anything about iridium, this site will have it. Exceptionally thorough.
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Handout
Other

Web ref.org: Iridium

For Students 9th - 10th
A student friendly site with basic information (and links to definitions or examples of key terms) on iridium. Good job on uses.