What is "tornesel"

The tornesel, tornesol, or was a silver coin of Europe in the late Middle Ages and the early modern era. It took its name from the , the of Tours. Marco Polo referred to the tornesel in recounts of his travels to East Asia when describing the currencies of the Yuan Empire. His descriptions were based on the conversion of 1 bezant = 20 groats = tornesel. The was a subunit of the Neapolitan, Sicilian, and Two Sicilies ducats.