Dinero 'prieto' - Alfonso X Coruna

The "prieto" designation — meaning dark or blackened — refers to the exceptionally low silver content in these billon issues, a deliberate debasement authorized under Alfonso X as his Castilian treasury struggled under the financial strain of his prolonged and ultimately failed campaign to claim the Holy Roman Imperial throne. That imperial ambition, which consumed vast resources between 1257 and 1275, forced repeated monetary manipulations that eroded public confidence in Castilian coinage and contributed directly to the baronial unrest of his later reign.

The Coruña mint was among several activated to meet demand during this period of high-volume, low-value production.