Oil

Oil can be found in the Swamp. It appears as a black stone formation on the ground in the water. It can best be harvested with a pickaxe.

Uses
Oil can be used as fuel for oil lamps, such as the lantern and burns for one hour per oil. It can also be used as a crafting material for steel compound, which is used to create steel.

Harvesting
Oil can be found in the Swamp and is best harvested with a pickaxe. One source contains 100 oil until it collapses, then it can only be harvested one per hit.