Lead is one of the base metals added by Thermal Foundation. It can be obtained from Lead Ore and, less commonly, Silver Ore.
Lead Ore and Silver Ore can also be processed in various ways in an Induction Smelter, with varying byproducts.
Like most base metals in the mod, Lead can be used to craft tools and armor. It can also be used to craft devices that can store Redstone Flux in Thermal Expansion. When combined with Obsidian, it can be used to create Hardened Glass.