Navajún is a municipality in the autonomous region of La Rioja, Spain. It was first mentioned in a document in 1381 due to donations made by Enrique II de Trastámara to Juan Ramirez de Arellano as thanks for his support in the fight against Peter the Cruel. The name of the city probably comes from the pre-Roman term Nava, which means width in Basque and is due to the fact that the city has an equal north-south and east-west extension.

Navajún is known worldwide for its pyrite mine, which was discovered in 1960 by the miner Pedro Ansorena. Perfect cubic pyrite cubes can be extracted here. The mine has never been used industrially, but only for mineralogical purposes. Particularly beautiful specimens can be found in all the major natural history museums.