In Gabriela Mistral's poem Ronda de los metales, one of the stanzas goes as follows (emphasis mine):
El cobre es arrebato,
la plata es maternal,
los hierros son Pelayos,
el oro Abderrahmán.
Translation:
Copper is rapture,
silver is maternal,
irons are Pelayos,
gold Abderrahmán.
The Spanish Wikipedia has disambiguation pages for Pelayo and Pelayos that make me none the wiser. Who or what are "Pelayos"?
The Islamic armies of Arabs and Moors conquered most of Spain in 711 and later years.
Pelagius (Spanish: Pelayo;1 c. 685 – 737) was a Hispano-Visigoth nobleman who founded the Kingdom of Asturias in 718.[2]
https://en.wikipedia.org/wiki/Pelagius_of_Asturias
So Pelayo is considered the first founder of the first Spanish kingdom after the Muslim conquest of Visigothic Spain. So I guess that Mistral said that iron was the metal for warriors like Pelayo who founded kingdoms and nations.
Abderrahman is obviously one of the many spellings of the Arab name Abd al-Rahman.
Five members of the Umayyad Dynasty named Abd al-Rahman became important in Spain.
Abd al-Rahman I (731-1788) was a prince of the Umayyad Dynasty who fled from its overthrow in 750 and made himself hereditary Emir in Spain in 756.
Abd al-Rahman II (788-852) was Emir of Spain.
Abd al-Rahman III (890-961) was Emir of Spain from 912. In 929 he proclaimed himself Caliph.
Abd al-Rahman IV (d.1018) was Caliph in 1018.
Abd al-Rahman V (d. 1048) was Caliph from 1023 to 1024.
And the association of wealth and gold with a Caliph seems obvious.
This supports the idea that iron is associated in the poem with Pelayos, fierce and successful warriors like Pelayo.
Don Pelayo (Pelagius in English), the Visigoth king of Asturias who initiated the Reconquista, is a very notable name in Spanish history, as described in M.A. Golding's answer. It was the first name that came into my head on reading the question, but on reflection I think that Mistral may be instead be referring to San Pelayo ("St Pelagius").
My reason is chiefly based on the proximity of the names "Pelayo" and "Abderrahmán" in Mistral's text. This Pelayo was being held as a hostage at the court of Abderrahmán (Abd al-Rahman III) in Cordoba, waiting to be ransomed by his family. When the money was not forthcoming, it seems that the king became enamored of Pelayo's physical beauty, and offered to make him a page if he renounced Christianity. Pelayo refused, and so the king had his body torn apart with iron tongs. He is commemorated in the calendar of saints by this epitaph:
Cordubæ, in Hispania, natalis sancti Pelagii adolescentuli, qui, ob confessionem fidei, Regis Saracenorum Abdarameni jussu forcipibus ferreis membratim præcisus, martyrium suum gloriose consummavit
At Córdoba, in Spain, the holy child Pelagius, who crowned his confession of the faith with a glorious martyrdom, by being torn to pieces with iron pincers, by order of Abdu’l-Rahman, King of the Saracens.
Thus San Pelayo has a direct connection with Abderrahmán, and also an association with iron - the iron tongs used to tear him apart, and also, perhaps, the strength of his faith. As Mistral was a Catholic, it also seems probable that she would be more familiar with a Catholic saint, than with a Spanish historical figure.
