Saltpetra, also known as potassium nitrate (KNO₃), is a naturally occurring mineral that has been historically used in fertilizers, food preservation, and as a key ingredient in gunpowder. It forms as a white crystalline substance and is soluble in water. In agriculture, it provides essential nutrients like potassium and nitrogen to plants, promoting healthy growth. Additionally, saltpetra has applications in the production of explosives and in the manufacturing of various chemicals.