The volcano on the island of Hierro, Spain, is called El Hierro (meaning "iron" in Spanish). However, its name doesn't come from the element iron.

There are two main theories about its name:

1. The Guanches: The indigenous people of the Canary Islands, the Guanches, called the island "Ezero" or "Hierro," which means "the sacred one" or "the holy one" in their language. This name might refer to the volcanic origin of the island, perceived as a mystical and powerful place.

2. The Portuguese: Another theory suggests that the name Hierro derives from the Portuguese word "ferro", meaning "iron," but not necessarily related to the metal itself. It could refer to the dark, volcanic rocks of the island, which resemble the color of iron.

Therefore, the most likely origin of the name El Hierro lies in the sacred connotations attributed to the island by the Guanches, rather than the presence of iron.