Iridium Dust
Iridium Dust is a byproduct of processing Depleted Coaxium Fuel Rods in a Thermal Centrifuge.
See the Single, Dual, and Quad Depleted Coaxium Fuel Rod pages for the specific numbers that you'll get.
Put it in a Compressor to get an Iridium Ore back.
Iridium Dust can be re-formed into Iridium Ore! Also, there is no way to craft Iridium Dust. HAYO!