Charcoal is a material added by vanilla Minecraft. It is the result of burning Wood blocks in a Furnace. Thermal Foundation adds a single item made of this material: Pulverized Charcoal.
Charcoal is most commonly used as a basic solid fuel. The material can also be processed in a Pulverizer to produce Pulverized Charcoal. This can be used as an ingredient to craft Gunpowder or Phyto-Gro.