Vulcanite is a new ore added with this mod that aims to improve your experience in the Nether. The armor has more durability against fire and the tools are enhanced as well. And it all starts with the Vulcanite ore.
The tools and armor are crafted differently than traditional tools and armor. You need to start with a base iron tool or armor piece and use an anvil with Vulcanite nuggets to get the desired item. There’s a handy guide found here for detailed information on how things are crafted and used with this mod.