Pyridium Ore is an ore that is found embedded into Netherrack in the Nether. Pyridium is colored orange, and is the Nether's equivalent of Diamonds in the overworld. They differ from other tools in the Nether, though. They and Linium share something in common, they both need Ghast Rods as sticks.
Pyridium is mined using a Neridium Pickaxe, and when mined, it will drop an Pyridium Ore block. Refine this ore in a furnace to get a Pyridium Ingot which can be used to make the tools and armor.