Gunpowder is a powder with element number 7 that is located in the Explosives section.
Gunpowder is bright grey (more bright than stone) which explodes upon contact with fire, plasma, lava and electricity. Heat of more than (400 C: 673 K) also lights it up. It's explosion is not very powerful, creating flames of around (600 C: 873 K) and pressure of 4.50 in a big pile. The explosion contains a lot of flames, though, and therefore easily lights flammable materials.
Gunpowder is a powdery form of low-power explosive, and can be used to enhance a material's burning factor, or just for controlled explosions.