The djinn that is locked up at Crowley's hideout asks Sam and Dean to help her. This is the same djinn (Played by Laura Mennell) that was after Sam and Dean, and eventually escaped from them, in season 6 episode 1.
Iridium is a very rare element. It's a brittle, silvery-white metal similar to platinum, in fact iridium is often found inside platinum and has to be extracted from it. Iridium is the second densest element (osmium being the densest). Only tiny amounts of iridium can be found naturally in the Earth's crust, most of the iridium on the planet came from meteors.