Gunpowder, used as a propellant in many primitive projectile weapons, typically consists of sulfur, some form of carbon, such as coal, and - more often than not - potassium nitrate.
Gunpowder used in 2267.
In 2267, Captain James T. Kirk manufactured gunpowder from the minerals available on a planetoid's surface in order to help him defeat the Gorn Captain in combat arranged by the Metrons. (TOS: "Arena")
The pre-industrial peoples of Neural were exposed to gunpowder centuries before they would have achieved the technology on their own. The Klingons sought influence over the planet, and through their agent, Krell, they introduced "fire sticks" to the village-dwelling population. The interference radically altered the lifestyle of the newly armed natives, who made war on their neighbors in 2268. James Kirk was forced to restore the balance of power by introducing the Hill People culture to gunpowder, and providing them with powerful new weapons. (TOS: "A Private Little War")