Nitre

"Is rock, but different."

- Wolfgang

Nitre is a mineral resource obtained by mining smooth Boulders and Stalagmites, which will drop at least one (along with other minerals) upon being mined. It also occasionally falls during underground Earthquakes. It is used to craft Gunpowder.

In the Reign of Giants DLC, it can be used to make Endothermic Fires and the Morning Star. Endothermic Fires can also be refueled with nitre.

Trivia

 * Nitre was added in the A Little Rain Must Fall update.
 * Nitre was changed to be dropped by the small, smooth boulder in The End of the Beginning update.
 * Nitre, aka Saltpeter (Potassium Nitrate), is a common ingredient in creating gunpowder in the real world. It is also an ingredient in fertilizer, although it cannot be used as fertilizer in game.