Also, use mercury cells in the industrial grinder when processing Sheldonite for increased yields (3 Pt, 1 Ni, & 2 Ir nuggets); since cinnabar is currently otherwise useless AFAIK.
Mercury cells can be made in a crafting table with empty cells and quicksilver, or you can acquire them as a byproduct of centrifuging other materials..
Well, yeah. I don't think that sheldonite gives iridium without using mercury.