Sulfur

Sulfur is commonly used in gunpowder, medicine, and matches. Matches release sulfur dioxide when they burn, giving them their smell. Sulfur is an essential component to living cells. Many proteins contain sulfur. It is also used as a pesticide on organic farms.

Sulfur | Rust Wiki

Crafted Item	Crafting Recipe
Incendiary Pistol Bullet	×10 ×10 ×5 ×3
Explosive 5.56 Rifle Ammo	×10 ×20 ×10 ×2
Incendiary 5.56 Rifle Ammo	×10 ×10 ×5 ×2
12 Gauge Incendiary Shell	×5 ×10 ×20 ×2
Explosives	×50 ×3 ×10 ×10 ×1
Gun Powder	×30 ×20 ×10