Humberstone and Santa Laura Saltpeter Works are two former saltpeter refineries located in northern Chile. They were declared a UNESCO World Heritage Site in 2005, as a testament to the historical importance of saltpeter mining in Chile and the culture and social agenda that developed around it in the late 19th century. The works were placed on the World Heritage List in Danger that same year, due to the fragility of the derelict buildings, but was removed in 2019.

Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter (or nitre in the UK). It is a source of nitrogen, and nitrogen was named after niter. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpeter (or saltpetre in the UK).